
Geometry Help
Looking for some Geometry Help? Our materials here review the basic terms and concepts in geometry and provide further lessons to help you develop your understanding of geometry and its applications to solving problems in real life.
Geometry is about the shape and size of things. It is the study of points, lines, angles, shapes, their relationships, and their properties.
Videos have been included in almost all the following topics to help reinforce your understanding.
Geometry Lessons
Basic
Geometry Terms  Points, Lines, Line Segments, Midpoints, Rays, Planes, Space
Pairs
of Lines 
Intersecting
Lines, Parallel Lines, Perpendicular
Lines, Skew Lines
Angles
Naming an
Angle, Angles Around a Point
Measuring Angles Using a Protractor
Drawing Angles Using a Protractor
Types
of Angles  Right Angles, Acute
Angles, Obtuse
Angles, Straight
Angles Pairs
of Angles
Complementary & Supplementary Angles
Vertical Angles,
Corresponding Angles,
Alternate Interior &
Exterior Angles
"Find the angle" problems
Triangles
Types
of Triangles
Right, Acute, Obtuse Triangles
Equilateral, Isosceles, Scalene Triangles
Special
Right Triangles
345 Triangles,
45°45°90° Triangles,
30°60°90° Triangles
Pythagorean
Theorem
Pythagorean Triples
Pythagorean Theorem Word Problems
Converse of the Pythagorean Theorem
Congruent
Triangles
SSS rule, SAS
rule, ASA rule, AAS rule
Hypotenuse Leg (HL)
Similar
Triangles  AA rule, RAR rule
Triangle Inequality 
Triangle Inequality Theorem, AngleSide Relationship
Triangle Sum Theorem
Exterior Angle Theorem
Interior Angles of a Triangle
Exterior Angles of a Triangle
Angles of a Triangle
Polygons
Quadrilaterals 
Parallelograms, Squares, Rhombus, Rectangles, Trapezoids
Types of Polygons
Angles in Polygons 
Sum
of Angles in a Triangle, Dividing
Polygons into Triangles, Formula for Sum
of Interior and Exterior Angles
Areas of Polygons
Areas of Squares and Rectangles
Areas of Parallelograms
Areas of Triangles
Area of Rhombus
Area of Trapezoids
Area of Shaded Region
Perimeters of Polygons 
Squares, Rectangles, Parallelograms, Triangle, Rhombus, Trapezoids
Circles
Circles
Diameter, Radius, Arc and Tangent of a Circle
Circumference of circle
Area of circle
Length of Arc in a circle
Area of Sector
Tangent to a Circle
Angles involving Tangents & Circles
Degrees and Radians
Arc Length of Circle in Radians
Circle Theorems
Chords of a Circle
The Arrow Theorem
The Bow Theorem
"90 Degrees in Semicircle" Theorem
Alternate Segment Theorem
Quadrilaterals in a Circle
Angles in a Circle
Angles and Intercepted Arcs
Solid Geometry
Volume of Solids
Volume of Cubes
Volume of Rectangular Prisms
Volume of Prisms
Volume of Cylinders
Volume of Spheres
Volume of Cones,
Volume of Pyramids
Surface Area of a Cube
Surface Area of a Prism
Surface Area of a Cylinder
Surface Area of a Cone
Surface Area of a Sphere
Surface Area of a Pyramid
Surface Area of Solids
Geometry Nets
Formulas Explained: Area of Cone, Volume of Cone, Volume of Sphere
Geometrical Formulas
Summary of shapes and formulas
Area Formula: rectangle, parallelogram. rhombus, triangle, regular polygon, trapezium, and circle
Surface Area Formula: sphere, closed cylinder, hollow cylinder, cone and pyramid
Volume Formula: solid cylinder, hollow cylinder, prism, cone, pyramid, and sphere
Coordinate Geometry and Graphs
Coordinate
Geometry
Coordinate Plane
Slope of a Line  yintercept, Negative Slope
Equation of a Line
Graphing Linear Equations
Slope and Intercept of a Linear Equation
Equation of a Line Parallel to the Xaxis or Yaxis
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 Lines, Slopes of Perpendicular Lines
Midpoint Formula
Distance Formula
Graphing Inequalities
Linear Programming
Graphing Quadratic Functions
Graphical Solutions of Quadratic Functions
Graphing Cubic Functions
Graphing Exponential Functions
Graphing Reciprocal Functions
Sketching the Graphs of some Functions
Geometric Construction
Geometric Construction
Construct and Copy Lines
Construct a Perpendicular Bisector
Construct a Perpendicular Line through a Point
Construct Parallel Lines
Construct a 60° Angle by Constructing An Equilateral Triangle
Construct an Angle Bisector
Construct a 30 Degree Angle
Construct a 45 Degree Angle
Construct A Triangle Given The Length Of Its Three Sides (SSS)
Construct A Triangle Given One Side And Two Angles
Construct A Triangle Given Two Sides And An Angle
Construct a Parallelogram and a Square
Contruct Various Angles & Shapes : 30°, 45 °, 90°, 120°; hexagon, triangle
Locus of a Moving Point
Geometry Transformation
Geometry / Math Tranformations
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 a decrease in size (reduction).
Geometry Proofs (Videos)
Triangle Medians and Centroids (2D Proof)
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 15,
Questions 610
Geometry Word Problems
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