4+4=? Trick Question :3

What basic trigonometric identity would you use to verify that sin x cos x tan x =1-cos^(2)x?

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.

Rectangle leg this 11feet and perimeter of 38feet what is the width of the rectangle in feet