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

Define an acute angle.

Back

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

Front

Define a right angle.

Back

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

Front

Define 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 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

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

What is a scalene triangle?

Back

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

Front

What is the formula to find the measure of an interior angle of a regular polygon?

Back

The formula is (n-2) * 180/n, where n is the number of sides.

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).