I’m unsure how to do this statistics problem I believe it has to do with the bell curve

Let us start subtracting 3 cos theta both sides so that we may get all theta terms on left side only

It is now : 4 cos theta - 3 cos theta = - (sqrt3)/ 2

1 cos theta = -( sqrt 3 ) /2

we know cos (pi-x)= - cos x And cos (pi+ x)= - cos (x)

let us first use :

- Cos ( pi - theta) = - ( sqrt 3 )/2

this implies cos (pi- theta )= (sqrt 3) /2

cos ( pi - theta )= cos (pi /6)

pi- theta = pi/6

pi- pi/6 = theta

5 pi/6 = theta

one of teh answer is 5 pi/6 . another value of theta would be :

(2pi - 5pi/6)= 7pi/6

5 pi/6 and 7 pi/6