Question

Question #b4d8f

Answer 1

`(2pi)/3,(4pi)/3`

Explanation:

`2costheta+1=0`

`rArrcostheta=-1/2`

`"since the ratio is negative " theta" will be in the"`
`"second and third quadrants"`

`rArrtheta=cos^-1(1/2)=pi/3larrcolor(red)" related acute angle"`

`rArrtheta=(pi-pi/3)=(2pi)/3larrcolor(blue)" second quadrant"`

`rArrtheta=(pi+pi/3)=(4pi)/3larrcolor(blue)" third quadrant"`

`rArrtheta=(2pi)/3,(4pi)/3to[0,2pi)`