12.9 Triangle Theorems

Front

What is the sum of the angles in a triangle?

Back

The sum of the angles in a triangle is always 180 degrees.

Front

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

Back

Subtract the sum of the two known angles from 180 degrees.

Front

What is the Triangle Inequality Theorem?

Back

The sum of the lengths of any two sides of a triangle must be greater than the length of the third side.

Front

What are remote interior angles in relation to an exterior angle?

Back

The remote interior angles are the two angles inside the triangle that are not adjacent to the exterior angle.

Front

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

Back

It is a right triangle.

Front

What is an isosceles triangle?

Back

An isosceles triangle has at least two sides that are equal in length.

Front

What is an equilateral triangle?

Back

An equilateral triangle has all three sides equal and all three angles measuring 60 degrees.

Front

How can you determine if three side lengths can form a triangle?

Back

Use the Triangle Inequality Theorem: a + b > c, a + c > b, and b + c > a.

Front

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

Back

In a triangle, larger angles are opposite longer sides.

Front

What is the formula for the area of a triangle?

Back

Area = 1/2 * base * height.