Which statements are true about the lines of symmetry of a regular pentagon? select three options.

Which is a true statement about an exterior angle of a triangle a. it is formed by two segments that are not sides of the triangle, b. it forms a linear pair with one of the interior angles of the triangle, c. it is complementary to one of the interior angles of the triangle. d. it is formed by two segments that are sides of the triangle.

He that is measured at 220° is a reflex angle. the opposite angle is obtuse. find the measure of obtuse .

Can someone me with #s 8, 9, and 11. with just one of the three also works. prove using only trig identities.