I need help answering these two questions

Prove sin2a + cos2a - 1 / sin2a + cos2a + 1 = 1 - tana / 1 + cota

Car a and car b were in a race .the driver of car b claimed that his car was twice as fast as car a

What is the arc length of the subtending arc for an angle of 72 degrees on a circle of radius 4? o a. 8a oc. 16 t d. 8