Question

Write the expression as a single trigonometric function: cos15cos75+sin15sin75

Answer 1

cos60 or sin30

Answer 2

\[\cos (u)\cos (v)\mp\sin (u)\sin (v)=\cos (u\pm v)\]

Answer 3

I'm not sure answer , do u missing i sin?

Answer 4

\[\text{Cos}[15{}^{\circ}]\text{Cos}[75{}^{\circ}]+\text{Sin}[15{}^{\circ}]\text{Sin}[75{}^{\circ}]=\frac{1}{2} \]