Question

if x=2costheta then show that
2(1+cos8theta)=(x^4-2x^2+2)^2​

Answer 1

Answer:

2(1 + cos8©) = 4cos²4©= 4(2cos²2©− 1)²

= 4(2(2cos²© - 1)² − 1)²

= (x² − 4x² + 2)²