1.

Prove that cos(π/4 + x) + cos(π/4 - x) = √2cosx

Answer»

LHS = cos(π/4)cosx - sin(π/4)sinx + cos(π/4)cosx + sin(π/4)sinx

= 2cos(π/4)cosx = 2(1/2)cosx = 2cosx

= RHS



Discussion

No Comment Found