SaiBook.us Geometry

Lesson Example Discussion Quiz: Class Homework

Lesson

Title: Angles

Grade: 6-a Lesson: S2-L4

Explanation: Hello students, let us learn a new topic in geometry today with definitions, concepts, examples, and worksheets included.

Lesson:

Definition: Interior Angle

Interior angles are formed when two sides of a polygon intersect at a vertex.
The sum of these angles depends on the number of sides and can be calculated using \$(n - 2) \times180\$ degrees, where "n" is the number of sides.

$1$

Explanation: In this image, the angles ∠a, ∠b, and ∠c are interior angles.

Definition: Exterior Angle

An exterior angle is an angle formed outside a polygon by extending one of its sides beyond the point where two other sides meet.
It is always supplementary to the adjacent interior angle, adding up to 180 degrees.

$2$

Explanation: In this image, the angles ∠a, ∠b, and ∠c are exterior angles.

Definition: Supplementary Angle

Supplementary angles are two angles that add up to 180 degrees.
One of the angles is acute, while the other is obtuse.
Additionally, both angles can be right angles.

$3$

Explanation: In the image, the angles with measures of 60 degrees and 120 degrees are supplementary angles because their sum is equal to 180 degrees.

Definition: Complementary

Complementary angles are a pair of angles that add up to 90 degrees (when added together).
In other words, two angles are considered complementary if the sum of their angle measures is exactly 90 degrees.

$4$

Explanation: In the image, the angles with measures of 60 degrees and 30 degrees are complementary angles because their sum is equal to 90 degrees.