Question

I have done half but i am not able to find angle in part2?

Answer 1

`theta = 0^circ, -109.5^circ, 109.5^circ`

Explanation:

Continuing from the factored equation

`(3costheta+1)(costheta-1) = 0`

Either `costheta = -1/3` or `costheta = 1`.

Solving `costheta = 1`:

Remember that `costheta` is an even function, so `cos(-theta) = costheta`. Essentially, if we find `theta` that satisfies the equation, `-theta` will also satisfy it.

`costheta = 1`

`theta = +-0^circ = 0^circ`

Solving `costheta = -1/3`:

`costheta = -1/3`

`theta ~~ +-109.5^circ`

The three solutions to the equation are `theta = 0^circ, -109.5^circ, 109.5^circ`.