Question

How do you solve `2costheta+1=0`?

Answer 1

The general solution of `2costheta+1=0` is :

`theta=2kpi+-(2pi)/3 ,k in ZZ`

Explanation:

Here,

`2costheta+1=0`

`=>2costheta=-1`

`costheta=-1/2 < 0=>costheta=(pi-pi/3)=cos((2pi)/3)`

So,

`costheta=cos((2pi)/3)towhere, theta=arc cos(-1/2)=(2pi)/3`

`=>theta=2kpi+-(2pi)/3 ,k in ZZ`