Thread: Solving trigonometric equations:

Solve for .

Here's my work:
sin(x) + sin(2x) = 0
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what do I do now? I can't think of any trig identities or anything to simplify it? Do i just do sin(x) = - sin(2x) which obviously isn't true, does anyone know??

Your pictures are broken. Try using Imageshack or some free image hosting. Or you can also upload to MHF, now that pictures appear to be working again.

Sorry about that, the picture is solve for sin(x) + 2*sin(x)*cos(x) = 0 for 0 degrees <= x < 180 degrees
I used a double angle idendtity to reduce from the aforementioned equation to sin(x) + sin(2x) = 0

Originally Posted by glambeth

Sorry about that, the picture is solve for for 0 degrees <= x < 180 degrees

Factor so
.

I see now, so x is equal to 0, 120, or 180?

since x is strictly less than 180 degrees you should not take that as the answer.

Thanks, no idea how I missed that!