Isosceles and Equilateral Triangles

Front

What is an isosceles triangle?

Back

An isosceles triangle is a triangle that has at least two sides of equal length.

Front

What is an equilateral triangle?

Back

An equilateral triangle is a triangle in which all three sides are of equal length and all three angles are equal to 60°.

Front

If two sides of a triangle are congruent, then the _________________ opposite those sides are congruent.

Back

angles

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

In an isosceles triangle, if the base angles are equal, what can be said about the vertex angle?

Back

The vertex angle is equal to 180° minus the sum of the base angles.

Front

If an isosceles triangle has a base angle measuring 40°, what is the measure of the vertex angle?

Back

100°

Front

What is the measure of each angle in an equilateral triangle?

Back

Each angle measures 60°.

Front

How do you find the measure of an unknown angle in a triangle?

Back

Subtract the sum of the known angles from 180°.

Front

If one angle of a triangle measures 90°, what type of triangle is it?

Back

It is a right triangle.

Front

What is the relationship between the sides and angles in a triangle?

Back

In a triangle, the larger the angle, the longer the opposite side.