8. 90° When a perpendicular line is drawn, the measure of both of the angles equal 90°.
9. Just draw two parallel lines, name them x and y. Then, draw a line through both of them and name it k.
10. Draw two parallel lines and draw a perpendicular line going through both r and s. All the angles will measure 90°.
11. Set it up like #9. and make the alternate interior angles congruent.
