Question

When you solve an equation like sin x = 0,5 why do you have to write both solutions and not just +- 30 + n * 360?

Answer 1

Mostly because `sin(-30^@) != 0.5`

Explanation:

The solutions to `sinx=0.5` (for angles, in degrees) are

`-690^@, -330^@, 30^@, 390^@, 750^@` --that is `30^@ +n360^@`

and

`-570^@, -210^@, 150^@, 510^@, 870^@` --that is `150^@ +n360^@`