Question

(cos⁴A-sin⁴A) is equal to​

Answer 1

Answer:

Step-by-step explanation:

sin 4a...but

cos 4a = cos 2(2a) =

cos^2 2a - sin^2 2a =

(cos^2 a - sin^2 a)^2 - (2 sin a cos a)^2 =

cos^4 a - 2 sin^2 a cos^2 a + sin^4 a - 4 sin^2 a cos^2 a =

cos^4 a + sin^4 a - 6 sin^2 a cos^2 a