Question

Please explain this answer ☹️

Answer 1

see explanation

Explanation:

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

cos45° = sin45° =
`(1)/(√(2) )` =
`(√(2) )/(2)`

Hence

12(cos315° + isin315°)

= 12(cos45° - isin45°)

= 12(
`(√(2) )/(2)` - i
`(√(2) )/(2)`)

= 6
`√(2)` - 6i
`√(2)`