hii guyzz, having trouble with MORE of these trig equations ><""

use the factors of xcubed - ycubed to show that

cos^6x - sin^6x = (1- 1/4sin^2x)cos2x

by the way, this ^means to the power to, and its just to the power of 6, and NOT to the power of 6x if anyone gets confued, the x is like theta

AND

if cosx = (a^2 - m^2)/(a^2 + m^2) and 0<x<pi/2 express tanx and sin2x in terms of a and m

thankyou sooooo much to anyone who can give me some help in these equations, i'm so grateful =D