SOLUTION: I am taking a trigonometry class right now and one of the equations I need help solving is: 2sin^2x+3sinx+1=0 From this equation I am required to use the quadratic formula,

Question 1000791: I am taking a trigonometry class right now and one of the equations I need help solving is:
2sin^2x+3sinx+1=0
From this equation I am required to use the quadratic formula, solve for all possible values of "x" and then find what angles "x" is on the unit circle.
I really am not sure how to solve this, I need some help. Thanks!
Answer by ikleyn(52788)   (Show Source): You can put this solution on YOUR website!
.
Hello,

introduce the new variable y = sin(x). You will get a quadratic equation for y

= .

Solve it and find y:   y = and y = -1.

Then determine x:

Case 1:   y =   --->   sin(x) =   --->   x = 210� + k*360� and x = 330� + k*360�.

Case 2:   y =   --->   sin(x) =   --->   x = 270� + k*360�

It is the standard way of solving non-linear equations.

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