Use Euler$$s identity to find trigonometric identities in terms of sin$(\backslash$alpha $),$ sin$(\backslash$beta $),$ cos$(\backslash$alpha $),$ and

cos$(\backslash$beta $)$:

a$)$ sin$(\backslash$alpha $+\backslash$beta $)$

b$)$ cos$(\backslash$alpha $+\backslash$beta $)$

Demonstrate all the steps in formula evaluation.