Question #70e43

1 Answer
Jan 24, 2018

x=90°, x=210°, x=330°

Explanation:

We want find the solution to:

2*sin^2(x)-sin(x)-1=0

Let u=sin(x)

2*u^2-u-1=0

Solve the quadratic equation

u=(-(-1)+-sqrt((-1)^2-(4*2*(-1))))/(2*2)=(1+-3)/4

Substitute u=sin(x)

sin(x)=(1+-3)/4

Therefore

sin(x)=-1/2 or sin(x)=1

Find the values for x in the interval

x=90°, x=210°, x=330°