Equilateral and Isosceles Triangles Practice

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, each measuring 60 degrees.

Front

What is an isosceles triangle?

Back

An isosceles triangle is a triangle that has at least two sides of equal length and the angles opposite those sides are also equal.

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 degrees.

Front

If two angles of a triangle are 50 degrees and 60 degrees, what is the measure of the third angle?

Back

The third angle measures 70 degrees.

Front

In an isosceles triangle, if one angle measures 40 degrees, what are the measures of the other two angles?

Back

The other two angles each measure 70 degrees.

Front

What does it mean for sides of a triangle to be congruent?

Back

Congruent sides are sides that are equal in length.

Front

If segment AB is the base of a triangle, what can you say about the angles opposite to it in an isosceles triangle?

Back

The angles opposite to segment AB are congruent.

Front

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

Back

To find the measure of an unknown angle, subtract the sum of the known angles from 180 degrees.

Front

What is the relationship between the sides and angles in an equilateral triangle?

Back

In an equilateral triangle, all sides are equal, and all angles are equal to 60 degrees.

Front

If two sides of a triangle are 5 cm and 5 cm, what can you say about the triangle?

Back

The triangle is isosceles because it has two sides of equal length.