#5.1 Angles of Triangles

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

Define 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 equal.

Front

What is a scalene triangle?

Back

A scalene triangle is a triangle in which all three sides are of different lengths and all three angles are of different measures.

Front

What is the definition of an obtuse triangle?

Back

An obtuse triangle is a triangle that has one angle measuring more than 90 degrees.

Front

If one angle of a triangle is 60 degrees and another is 70 degrees, what is the measure of the third angle?

Back

The third angle measures 50 degrees (180 - 60 - 70 = 50).

Front

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

Back

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

Front

What is the relationship between the angles in a right triangle?

Back

In a right triangle, one angle is exactly 90 degrees, and the sum of the other two angles is 90 degrees.

Front

What is the exterior angle theorem?

Back

The exterior angle theorem states that the measure of an exterior angle of a triangle is equal to the sum of the measures of the two non-adjacent interior angles.

Front

If two angles of a triangle are 45 degrees and 55 degrees, what is the measure of the third angle?

Back

The third angle measures 80 degrees (180 - 45 - 55 = 80).