### Home > GC > Chapter 5 > Lesson 5.3.5 > Problem 5-120

Examine trapezoid below.

Find the measures of all the angles in the diagram.

The corresponding angles are equal.

Since line

line , then corresponding angles.

So, mark it on your diagram.

While lineline , then corresponding angles.

So, mark it on your diagram. Use the Triangle Angle Sum Theorem.

Now you know two angles in

and , knowing that one angle is and .

Calculate the third angle using the equation.

So the missing angle is. Mark it in your diagram. The angles at

*E*form a straight angle, which is. Since

and then .

Solve for, mark it on your diagram. . The alternate interior angles are equal.

Since

and , then and because alternate angles are equal. Mark the angles on your diagram. What is the sum of the angles that make up the trapezoid

? That is, what is?

Note: Do not add in the angles at.