Question

Find the number of solutions for the given equation for 0° ≤ θ ≤ 360°.

sin2x - 2sinx - 3 = 0

Answer 1

Assume sinx = x

x^2 - 2x - 3 = 0
and factorize it

Answer 2

You know how to factorize right ?
you can factorize it like any other equation
(sinx + 1)(sinx - 3) = 0

sinx = -1
sinx = 3 (not accepted) sinx can't be greater than 1

sinx = -1 so
it's the 3rd, 4th quart

Answer 3

so it's x = 360 - 90 = 270
and x = 180 +90 = 270
same answer so
x = 270