trigonometric equation help

Question

sin^2(x) - 3sin(x) + 2 = 0 within [-4π, 4π]

Answer 1

Let y = sin(x)

Then the given equation becomes

y² - 3y + 2 = 0

(y - 1)(y - 2) = 0

y = 1 (Note that 2 cannot be a value for a sine function)

x = arcsin(1) = π/2