Question

cos⁴theta -sin⁴theta =2cos²theta-2=1-2sin²theta​

Answer 1

Answer:

cos^4theta _sin^4theta=(cos^2theta+sin^2thet)×(cos^2theta-sin^2 theta)

(cos^2theta-sin^2theta)×1

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

2cos^2theta-1