What is the answer to > solve 4cos (theta/3) -2 = 0, over [0, 4pi)

Hello from MrBillDoesMath!

@ =   pi/3 (or 60 degrees) or @ = 7 pi/3 (or 420 degrees)

Discussion:

Let "@' denote the angle "theta". We are asked to find @ in the interval [0, 4 pi)

where

4cos(@) - 2 = 0.                Adding 2 to both sides

4 cos(@) - 2 +2 = 2  =>

4 cos(@) = 2                     Divide both sides by 4

cos(@) = 2/4 = 0.5

This implies that @ =   pi/3 (or 60 degrees) or @ = (pi/3 + 2pi) = 7 pi/3 (or 420 degrees)

Thank you,

MrB

i used to know how to do this in 7th but i forget easily

step-by-step explanation:

correct answer:

b.(19,-2)