Question

Question #ce9db

Answer 1

`cos 3theta=44/125=0.352`

Explanation:

`sin theta=3/5 ; cos theta=sqrt(1-(3/5)^2)=4/5`
`costheta =-4/5` when `theta` is in between `90^0 & 180^0`
`cos 3theta=4cos^3theta-3costheta= 4*(-4/5)^3-3*(-4/5) = -256/125+12/5=44/125=0.352`[Ans]