Solving Trigonometry Polynomial Equation.

Question

I am trying to understand how to solve the equation

$$2\sin^2x + 3\sin x + 1 = 0.$$

Please give hints.

Hi, welcome to math.SE! Can you show what you've done so far, and what you're having trouble with? We prefer to help you understand and solve things on your own, rather than being a homework-solving service.
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Nevermind, I just had to factor it into (sinx + 1)(2sinx + 1).
@EricNaslund The edited version of this question does not only change the tone slightly, rather it contradicts explicit demands made by the OP in the original version, namely, to solve this for them and to show the steps, ASAP. One might view such a modification as problematic.

Jonathan Christensen · Answer 1 · 2012-12-21 00:16:55Z

up vote 6 down vote

Hint: Let $y=\sin x$. Solve for $y$ first, then solve for $x$.

edited Dec 21 '12 at 0:16

answered Dec 20 '12 at 23:42

Jonathan Christensen
3,147320

Eric · Answer 2 · 2012-12-20 23:43:35Z

up vote 4 down vote

Just treat $\sin x$ as a variable, and solve the polynomial.

edited Dec 20 '12 at 23:43

Eric
33.3k576143

answered Dec 20 '12 at 23:42

Ken
412

2 Answers