Definitions When two lines are crossed by another line (Transversal), Consecutive Interior Angles are the pairs of angles on one side of the transversal, but inside the two lines. The 2 angles in purple (d and e) make one pair of consecutive interior angles, and the other 2 angles in red (c and f) make another … Continue reading "Consecutive Interior Angles"

Read More# Category: Geometry

## Parallel Lines

Lines are parallel if they are always the same distance apart (called “equidistant“), and will never meet. Definition of Parallel Lines Parallel lines in geometry are lines in a plane which do not meet. They don’t intersect each other at any point. By extension, a line & a plane, or 2 planes, in 3D Euclidean … Continue reading "Parallel Lines"

Read More## Angles

Definition An angle measures the amount of turn Names of Angles As the Angle Increases, the Name Changes: Type of Angle Description Illustration Acute Angle is less than 90° Right Angle is 90° exactly Obtuse Angle is greater than 90° butless than 180° Straight Angle is 180° exactly Reflex Angle is … Continue reading "Angles"

Read More## Cuboid

Cuboids are familiar objects you encounter in daily life numerous times. Cuboids are essentially boxes, formed exclusively from rectangles. These familiar shapes are also known as rectangular prisms. Definition of Cuboid The cube is a 3D structure which is formed when 6 identical squares bind to each other in an enclosed form. Remember all cubes … Continue reading "Cuboid"

Read More## Supplementary Angles

Definition 2 Angles are Supplementary when they add up to 180 degrees. Supplement comes from Latin supplere, to complete or “supply” what is needed. These two angles (120° and 60°) are Supplementary Angles, because they add up to 180° and make a straight angle. But the angles don’t have to be together. These 2 angles … Continue reading "Supplementary Angles"

Read More## Vertically Opposite Angles

Vertically Opposite Angles Definition Vertically Opposite Angles are the angles opposite each other when 2 lines cross Vertical in this case means they share the same corner point (vertex), not the usual meaning of up-down. a and c are vertically opposite angles. b and d are also vertically opposite angles. The interesting thing here is that vertically opposite angles are … Continue reading "Vertically Opposite Angles"

Read More## Congruent Angles

In geometry, 2 figures or objects are congruent if they have the same shape and size, or if one has the same shape and size as the mirror image of the other. Definitions of Congruent Angles Angles are congruent if they have the same angle measure in degrees. They can be at any orientation on … Continue reading "Congruent Angles"

Read More## Complementary Angles

Complementary comes from Latin completum meaning “completed“, because the right angle is thought of as being a complete angle. Definition of Complementary Angles Complementary angles are 2 angles whose measures add up to 90o. For example 2 puzzle pieces that form one 90o angle when they are put together. Complementary angles are always in a pair. One … Continue reading "Complementary Angles"

Read More## How To Find if Triangles are Congruent

Triangles are congruent when all corresponding sides & interior angles are congruent. The triangles will have the same size & shape, but 1 may be a mirror image of the other. 2 triangles are congruent if they have: exactly the same three sides and exactly the same three angles. We don’t have to know all 3 … Continue reading "How To Find if Triangles are Congruent"

Read More## Volume and Area of a Sphere

Definition A sphere is a perfectly round geometrical object in 3D space that is the surface of a completely round ball. Sphere Facts Here are some interesting facts about sphere: It is perfectly symmetrical All points on the surface are the same distance “r” from the center It has no edges or vertices (corners) It … Continue reading "Volume and Area of a Sphere"

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