Triangle Theorems

Front

What is a triangle?

Back

A triangle is a polygon with three edges and three vertices. It is one of the basic shapes in geometry.

Front

What is the sum of the interior angles of a triangle?

Back

The sum of the interior angles of a triangle is always 180°.

Front

What is an acute triangle?

Back

An acute triangle is a triangle where all three interior angles are less than 90°.

Front

What is a right triangle?

Back

A right triangle is a triangle that has one angle measuring exactly 90°.

Front

What is an obtuse triangle?

Back

An obtuse triangle is a triangle where one of the interior angles is greater than 90°.

Front

What are complementary angles?

Back

Complementary angles are two angles that add up to 90°.

Front

What are supplementary angles?

Back

Supplementary angles are two angles that add up to 180°.

Front

What is the relationship of alternate interior angles when two parallel lines are cut by a transversal?

Back

Alternate interior angles are equal.

Front

What is the relationship of corresponding angles when two parallel lines are cut by a transversal?

Back

Corresponding angles are equal.

Front

What is the exterior angle theorem?

Back

The exterior angle of a triangle is equal to the sum of the two opposite interior angles.