Question

Prove : Cos^4A+sin^4A=1/4(3+cos4A)

Answer 1

Answer:

1 = (sin^2 A + cos^2 A)^2 = sin^4 A + cos^4 A + 2 sin^2 A cos^2 A

so

sin^4 A + cos^4 A

= 1 - 1/2 sin^2 2A

= 1 - 1/4 (1- cos 4A)

= 1/4 (3+cos 4A)

Step-by-step explanation:

hope I helped