prove sin^4 theta - cos^4 theta = 2sin ^2 theta - 1

Answer:

sin^4 theta - cos^4 theta = (sin^2 theta + cos^2 theta)x

(sin^2 theta - cos^2 theta)

** (difference of two squares)**

= (1)(sin^2 theta - cos^2 theta)

= sin^2 theta - cos^2 theta

= sin^2 theta - (1 - sin^2 theta)

= 2sin^2 theta - 1 as required

Good Luck!

hollownomore.