Question

Cos^2(75)-sin^2(45)=?
Plz answer this question

Answer 1

what u have a main problem with this question is cos^2(75)

so write cos^75 as cos(45 + 30)
and then use the formula of cos(A + B) = cosAcosB - sinAsinB

put the standard values of on solving and u will get your answer