Question

Please explain this answer ☹️

Answer 1

Answer:

see explanation

Step-by-step explanation:

Note that cos315° = cos45° and sin315° = - sin45° and

cos45° = sin45° = $\frac{1}{\sqrt{2} }$ = $\frac{\sqrt{2} }{2}$

Hence

12(cos315° + isin315°)

= 12(cos45° - isin45°)

= 12($\frac{\sqrt{2} }{2}$ - i $\frac{\sqrt{2} }{2}$)

= 6$\sqrt{2}$ - 6i $\sqrt{2}$