cos^2acos^2b-sin^2asin^2b=cos^2a-sin^2b
Answers
Answered by
0
= (cosa cosb)^2 - (sina sinb)^2
= (cosa cosb - sina sinb) + (cosa cosb + sina sinb)
= cos(a-b)cos(a+b)
= cos^2a-sin^2b
Similar questions