Question

Question #a7330

Answer 1

`A= 60^@ + k * 360^@`
or
`A=180^@+k * 360^@`
`color(white)(*"XXXXX")k in ZZ`

Explanation:

`cos(60^@) = 1/2color(white)("XXX")`(this is one of the standard angles)

`rarr sin(A-30^@)=1/2`

If `(A-30^@)` is restricted to `[0,360^@)`
`rarr (A-30^@) = 30^@ or 150^@`

`rarr A= 60^@ or 180^@`

If `(A-30^@)` is not restricted then the cycle will reoccur every `360^@`

`A=60^@+k * 360^@ or 180^@+k * 360^@, AAk in ZZ`