Angles in 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

What is an acute angle?

Back

An acute angle is an angle that measures less than 90 degrees.

Front

What is a right angle?

Back

A right angle is an angle that measures exactly 90 degrees.

Front

What is an obtuse angle?

Back

An obtuse angle is an angle that measures more than 90 degrees but less than 180 degrees.

Front

What is the exterior angle theorem?

Back

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

Front

If one angle of a triangle is 40 degrees and another is 60 degrees, what is the measure of the third angle?

Back

The third angle measures 80 degrees (180 - 40 - 60 = 80).

Front

What is the relationship between the angles in an isosceles triangle?

Back

In an isosceles triangle, the angles opposite the equal sides are equal.

Front

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

Back

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

Front

What is the formula for the sum of angles in a triangle?

Back

The formula for the sum of angles in a triangle is: Angle1 + Angle2 + Angle3 = 180 degrees.

Front

If two angles in a triangle are 50 degrees and 70 degrees, what is the measure of the third angle?

Back

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