Geometry Help (video lessons, examples, solutions, worksheets, activities, games) (2024)

Popular Topics In Geometry

Geometry Topics
AnglesTrianglesPolygons
Circles Circle TheoremsSolid Geometry
Geometric FormulasGeometric Constructions
TransformationsGeometric ProofsPractice Questions

Examples, solutions, and videos have been included in almost all the following topics to help reinforceyour understanding.

Introduction To Geometry

  • Geometry Terms

    Basic Geometry Terms
    Points, Lines, Collinear, Line Segments, Midpoints, Rays, Planes, Coplanar, Space
    Pairs of Lines
    Intersecting Lines, Parallel Lines, Perpendicular Lines, Skew Lines

Angles

  • Introduction To Angles

    Angles
    How to Name an Angle. Angles Around a Point.
    Measuring Angles
    How to use a protractor to measure an angle.
    Drawing Angles
    How to use a protractor to draw different types of angles

  • Types Of Angles

    Types of Angles
    Right Angles, Acute Angles, Obtuse Angles, Straight Angles, Reflex Angles and Full Angles
    Pairs of Angles
    Complementary, Supplementary, Vertical, Corresponding, Alternate Interior, Alternate Exterior and Adjacent Angles

    Solve problems using Complementary and Supplementary Angles
    Vertical Angles
    Solving problems using Vertical Angles, Proof of the Vertical Angle Theorem
    Corresponding Angles
    Corresponding Angle Theorem, Converse of the Corresponding Angle Postulate

    Alternate Interior Angle and Alternate Exterior Angle Theorems, Proofs and Converse
    “Find the angle” problems
    Summary of all the different angle properties and how they can be used to find missing angles



Triangles

  • Types Of Triangles

    Types of Triangles
    Right, Acute, Obtuse, Equilateral, Equiangular, Isosceles, Scalene. Oblique Triangles
    Triangles
    Right, Acute, Obtuse
    Triangles
    Equilateral, Isosceles, Scalene
    Special Right Triangles
    3-4-5 Triangles, 5-12-13 Triangles, 45-45-90 Triangles, 30-60-90 Triangles
    3-4-5 Triangles
    45-45-90 Triangles
    30-60-90 Triangles

  • Pythagorean Theorem

    Pythagorean Theorem
    How to use the Pythagorean Theorem, Converse of the Pythagorean Theorem, Worksheets, Pythagorean Theorem Proofs
    Pythagorean Triples
    Examples of Pythagorean Triples, Families of Pythagorean Triples, Pythagorean Triples and Right Triangles,Solving Problems using the Pythagorean Triples, How to generate Pythagorean Triples
    Pythagorean Theorem Word Problems
    How to use the Pythagorean Theorem to solve word problems
    Converse of the Pythagorean Theorem
    Explain how to use the Converse of the Pythagorean Theorem. Proof of the Converse of the Pythagorean Theorem

  • Congruent Triangles
    SSS rule, SAS rule, AAA rule, AAS rule, HL rule for congruent triangles, CPCTC
    SSS rule, SAS rule, ASA rule, AAS rule
    Explain the rules, How to use two-column proofs to prove triangles congruent
    Hypotenuse Leg (HL)
    Why HL is sufficient to prove two right triangles congruent and How to use HL postulate in two-column proofs
    Similar Triangles
    Properties of similar triangles, AA rule, SAS rule, SSS rule, Solving problems with similar triangles

  • Triangle Theorems

    Triangle Inequality
    Triangle Inequality Theorem, Angle-Side Relationship
    Triangle Sum Theorem
    Proof of the Triangle Sum Theorem. How to use the Theorem to solve geometry problems involving triangles
    Exterior Angle Theorem
    How to use the Exterior Angle Theorem, How to prove the Exterior Angle Theorem
    Interior Angles of a Triangle
    Properties of Interior Angles, Solve problems involving interior angles
    Exterior Angles of a Triangle
    Find unknown exterior angles, Proof the sum of exterior angles
    Angles of a Triangle
    Summary of the properties of angles in a triangle

  • Law Of Sines And Cosines

    Law of Sines or Sine Rule
    How to use the Law of Sines, Ambiguous case, Proof for the Law of Sines, Applications using the Law of Sines
    Law of Cosines or Cosine Rule
    How to use the Law of Cosines, Proof for the Law of Cosines, Applications using the Law of Cosines
    Solving a Triangle - SAS - Finding Missing Sides/Angles
    How to solve triangles using the Law of Sines



Polygons

  • Introduction To Polygons

    Polygons
    Types of Polygons:simple or complex, convex or concave, equilateral,equiangular, regular or irregular, Naming Polygons
    Angles in Polygons
    Sum of Anglesin a Triangle, Dividing Polygons into Triangles, Formulafor the Sum of Interior and Exterior Angles of a Polygon
    Quadrilaterals
    Parallelogram,Square, Rhombus, Rectangle, Trapezoid, Kite, Trapezium
    Polygons
    Describe the characteristics of a polygon

  • Area of Polygons
    Formulas for the area of Square, Rectangle, Parallelogram, Triangle, Rhombus, Kite, Trapezoid, any Regular Polygon
    Area of Squares and Rectangles
    Formulas and practice for the area of Square and Rectangle
    Area of Parallelograms
    Formula for the area of a parallelogram, Derive the formula for the area of a parallelogram, Word problems usingparallelograms
    Area of Triangles
    Use of the different formulas to calculate the area of triangles, given base and height, given three sides,given side angle side, given equilateral triangle, given triangle drawn on a grid, given three verticeson coordinate plane, given three vertices in 3D space
    Area of Rhombus
    Use of the different formulas to calculate the area of rhombus, given base and height, given lengths of diagonals,given side and angle
    Area of Trapezoids
    Area of trapezoids, Derive area formula of trapezoids, Solve problems using area of trapezoids
    Area of Shaded Region
    How to calculate the area of shaded regions involving polygons and circles.
    Perimeters of Polygons
    Squares, Rectangles, Parallelograms, Triangle, Rhombus, Trapezoids, Word Problems involving perimeters of polygons

Circles

  • Parts Of A Circle

    Circles
    Diameter, chord, radius, arc, semicircle, minor arc, major arc, tangent, secant, circumference, area, sector
    Parts of a circle
    Diameter, Chord, Radius, Arc, Tangent, Intersecting Circles, Internal and External Tangents

  • Circumference of circle
    Find pi, Formula for circumference of circle, Find circumference, Find radius, diameter and area whengiven circumference
    Arc of a Circle
    Arc of a circle, Central Angle, Arc Measure, Arc Length Formulas for arcmeasure given in degrees or in radians.
    Area of circle
    Formula for area of circle, Find area, Find radius, diameter and circumference when given area
    Area of Sector
    Area of a sector formula in degrees and radians, area of segment
    Area of Shaded Region
    How to calculate the area of shaded regions involving polygons and circles.

  • Tangents Of Circles

    [Tangent to a Circle
    Point of Tangency, Tangent to a Circle Theorem, Secant, Two-Tangent Theorem, Common Internaland External Tangents

    Find angles involving Tangents and Circles

  • Degrees and Radians
    Measure angles in degrees, minutes and seconds, Convert to decimal notation, Add and subtractangles, Measure angles in radians, Convert between degrees and radians
    Arc Length of Circle in Radians
    Formula for arc length when arc measure is in radians, Solving problems using arc length formula
    Area of Sector
    Area of a sector formula in degrees and radians, area of segment

Circle Theorems

  • Chords of a Circle
    Perpendicular bisector of a chord passes through the center of a circle, Congruent chords areequidistant from the center of a circle, If two chords in a circle are congruent, then theirintercepted arcs are congruent, If two chords in a circle are congruent, then they determinetwo central angles that are congruent.
    Angles and Intercepted Arcs
    Formulas relating the angles and the intercepted arcs of circles.
    Measure of a central angle.
    Measure of an inscribed angle (angle with its vertex onthe circle)
    Measure of an angle with vertex inside a circle.
    Measure of an angle with vertex outside a circle.

  • Angles In A Circle

    The Inscribed Angle Theorem
    Inscribed angles and central angles, The Inscribed Angle Theorem or The Central Angle Theorem orThe Arrow Theorem.
    The Bow Theorem
    Inscribed angles subtended by the same arc or chord are equal.
    Thales' Theorem
    Triangle inscribed in semicircle orAngle inscribed in semicircle or ӹ0 degrees in SemicircleTheorem or Thales' Theorem
    Alternate Segment Theorem
    An angle between a tangent and a chord through the point of contact is equal to the angle in thealternate segment.
    Quadrilaterals in a Circle
    Cyclic Quadrilateral, the opposite angles of a cyclic quadrilateral are supplementary, theexterior angle of a cyclic quadrilateral is equal to the interior opposite angle.
    Angles in a Circle
    A review and summary of the properties of angles that can be formed in a circle and their theorems.

Solid Geometry

  • Volume Of Solids

    Volume of Cubes
    What is volume, how to find the volume of a cube, how to solve word problems about cubes, netsof a cube.
    Volume of Rectangular Prisms
    How to find the volume of a rectangular prism, how to solve word problems about rectangularprisms
    Volume of Prisms
    What is a prism, how to find the volume of prisms, how to solve word problems about prisms.
    Volume of Cylinders
    How to find the volume of cylinders, how to find the volume of hollow cylinders or tubes, howto solve problems about cylinders.
    Volume of Spheres
    How to find the volume of a sphere, how to find the volume of a hemisphere, how to prove theformula for the volume of a sphere.
    Volume of Cones
    What is a cone, how to calculate the volume of a cone, how to solve word problems about cones,how to prove the formula of the volume of a cone.
    Volume of Pyramids
    What is a pyramid, how to find the volume of a pyramid, how to solve word problems aboutpyramids, the relationship between the volume of a pyramid and the volume of a prism with thesame base and height.

    Volume and surface area of cubes, cuboids, prisms, cylinders, spheres, cones, pyramids

  • Surface Area Of Solids

    Surface Area of a Cube
    How to calculate the surface area of a cube, how to find the length of a cube given thesurface area, nets of a cube.
    Surface Area of a Cuboid
    How to calculate the surface area of a cuboid, how to solve word problems about cuboids,nets of a cuboid.
    Surface Area of a Prism
    Calculate the surface area of prisms: rectangular prisms, triangular prisms, trapezoidalprisms, hexagonal prisms etc., solve problems about prisms. calculate the surface areaof prisms using nets.
    Surface Area of a Cylinder
    Calculate the surface area of solid cylinders, calculate the surface area of hollow cylinders,solve word problems about cylinders, calculate the surface area of cylinders using nets.
    Surface Area of a Cone
    Calculate the surface area of a cone when given the slant height, calculate the surface areaof a cone when not given the slant height, solveword problems about cones, derive theformula for the surface area of a cone
    Surface Area of a Sphere
    Calculate the surface area of a sphere, calculate the surface area of a hemisphere, solveproblems about surface area of spheres, prove the formula of the surface area of a sphere.
    Surface Area of a Pyramid
    Find the surface area of any pyramid, find the surface area of a regular pyramid, find thesurface area of a square pyramid, find the surface area of a pyramid when the slant heightis not given.
    Geometric Nets
    Nets of solids: cubes, cuboids, triangular prisms, prisms, pyramids, cylinders, cones.
    Surface Area of Solids
    Using nets to calculate the surface area of solids: cube, rectangular prism or cuboid,triangular prism, cylinder, and pyramids

Geometric Formulas

  • Area, Surface Area, Volume Formulas

    Area Formula:
    Gives the area formula for square, rectangle, parallelogram. rhombus, triangle, regular polygon,trapezoid (trapezium), circle and ellipse.
    Surface Area Formula:
    Gives the surface area formula for cube, cuboid, prism, solid cylinder, hollow cylinder, cone,pyramid, sphere and hemisphere
    Volume Formula:
    Gives the volume formula for cube, cuboid, prism, solid cylinder, hollow cylinder, cone, pyramid,sphere and hemisphere
    Formulas Derived:
    Area of Cone, Volume of Cone, Volume of Sphere
    Summary of shapes and formulas
    Describes the common geometrical shapes and the formulas to calculate their area and perimeter.It also includes the use of the Pythagorean Theorem and Heron’s formula.

Coordinate Geometry And Graphs

  • Coordinate Plane

    Coordinate Geometry
    Coordinate plane, Slope Formula, Equation of a Line, Slopes of parallel lines, Slope ofperpendicular lines, Midpoint Formula, Distance Formula
    Coordinate Plane
    The coordinate plane or Cartesian plane, points on the Cartesian Plane, quadrants

  • Equation Of A Line

    Slope of a Line
    Slope of line from the graph (rise over run), using the slope formula, negative slope, y-intercept
    Equation of a Line
    The slope-intercept form for the equation of a line, how to write equations in slope-interceptform, how to write equations of horizontal and vertical lines, how to get the equation of aline given two points on the line.
    Forms of Linear Equations
    The slope-intercept form, the point-slope form, the general form, the standard form, how to convertbetween the different forms of linear equations.
    Explore the straight line graph
    Activity to investigate how the change of the slope and y-intercept can affect the straight line graph.
    Equation of a Line Parallel to the X-axis or Y-axis
    Equation of a Line Given its Slope and a Point on the Line
    Equation of a Line Given Two Points on the Line
    Slopes of Parallel and Perpendicular Lines
    How to determine if two lines are parallel or perpendicular when given their slopes, how to findthe equation of a line given a point on the line and a line that is parallel or perpendicular toit, how to find parallel or perpendicular lines using Standard Form.

  • Graphs Of Linear Equations

    Graphing Linear Equations
    How to graph linear equations by plotting points, how to graph linear equations by findingthe x-intercept and y-intercept, how to graph linear equations using the slope and y-intercept.
    Slope and Intercept of a Linear Equation
    How to graph a linear equation when the equation is given in slope-intercept form or whenthe equation is given in general form.

  • Midpoint Formula
    The midpoint formula, how to find the midpoint given two endpoints, how to find one endpointgiven the midpoint and another endpoint, how to proof the midpoint formula.
    Distance Formula
    How to derive the distance formula from the Pythagorean Theorem, how to use the distance formula.

  • Graphs Of Linear Inequalities

    Graphing Linear Inequalities
    Graph of linear inequalities, how to graph linear inequalities, how to graph systems of linearinequalities.
    Graphing Inequalities
    Linear Programming
    Linear programming, how to use linear programming to solve word problems.

  • Graphs Of Quadratic Functions

    Quadratic Functions
    The different forms of quadratic functions, general form, factored form, vertex form, convertfrom general form to factored form, convert from the general form to the vertex form usingthe vertex formula, convert from the general form to the vertex form using completing the square.
    Graphing Quadratic Functions
    How to graph of quadratic functions by plotting points, how to graph quadratic function of the form y =ax2, the properties of the graph y = ax2, how to graph a quadraticfunction given in general form, how to graph a quadratic function given in factored form, how tograph a quadratic function given in vertex form.
    Graphical Solutions of Quadratic Equations
    How the solutions of a quadratic equation is related to the graph of the quadratic function,how to use the graphical method to solve quadratic equations.

  • Graphing Cubic Functions
    How to graph of cubic functions by plotting points, how to graph cubic functions of theform y = a(xh)3 + k.
    Graphing Exponential Functions
    How to graph exponential functions by plotting points, the characteristics of exponentialfunctions, how to use transformations to graph an exponential function.
    Graphing Reciprocal Functions
    How to graph reciprocal functions by plotting points, the characteristics of graphs ofreciprocal functions, how to use transformations to graph a reciprocal function, how toget the equation of a reciprocal function when given its graph.
    Sketching the Graphs of some Functions
    How to graph functions of the form y = axn + c, how to sketch some basic or common graphs.



Geometric Constructions

  • Construct Lines

    Geometric Construction
    Construct and Copy a Line Segment
    Construct the Perpendicular Bisector of a Line Segment
    Construct a Perpendicular Line through a Point
    How to construct a perpendicular to a line through a point on a line. how to construct aperpendicular to a line through a point not on a line.
    Construct Parallel Lines
    How to construct parallel lines, how to construct a line parallel to another line and through agiven point.

  • Construct a 60° Angle by Constructing An Equilateral Triangle
    Construct an Angle Bisector
    How to construct an angle bisector of a given angle, how to use an angle bisector to construct someangles for example, 90°, 45°, 60°, 30°, 120°, 135°, 15°.
    Construct a 30-Degree Angle
    Construct a 45° Angle
    Construct A Triangle
    Given the Length of its Three Sides (SSS)
    Construct A Triangle
    Given One Side and Two Angles (ASA)
    Construct A Triangle
    Given Two Sides and an Angle (SAS)

    How to construct a parallelogram given the lengths of its sides and an angle, how to construct aparallelogram given the lengths of its diagonals, how to construct a square given the length ofthe diagonal, how to construct a square given the length of one side.

    30° 45° 90° 120° hexagon, triangle

  • Locus Of Points

    Locus of a Moving Point
    The rules of the Locus Theorem, how the rules of the Locus Theorem can be used in real worldexamples, how to determine the locus of points that will satisfy more than one condition.

Geometric Transformations

  • Types Of Transformations

    Geometry / Math Transformations
    Translation, Reflection, Rotation, Dilation or Enlargement
    Translation
    Involves sliding the object from one position to another.
    Reflection
    Involves flipping the object over a line called the line of reflection.
    Rotation
    Involves turning the object about a point called the center of rotation.
    Dilation
    Involves a resizing of the object. It could result in an increase in size (enlargement) or adecrease in size (reduction).

Geometric Proofs

  • 2-Dimensional Proofs
    Triangle Medians and Centroids
    Area Circumradius Formula Proof
    Proof that the diagonals of a rhombus are perpendicular bisectors of each other

Geometry Practice Questions

Free SAT Practice Questions (with Hints & Solutions) - Geometry

  • Questions 1-5
    Questions 6-10
    Geometry Word Problems

Try the free Mathway calculator andproblem solver below to practice various math topics. Try the given examples, or type in your ownproblem and check your answer with the step-by-step explanations.



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Geometry Help (video lessons, examples, solutions, worksheets, activities, games) (2024)
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