Posted by Trig on Thursday, July 4, 2013 at 4:14pm.
Find all solutions in the interval [0,2pi].
sin 2x + sin x = 0

trig  Damon, Thursday, July 4, 2013 at 5:25pm
sin 2 x = 2 sin x cos x
2 sin x cos x + sin x = 0
sin x (2 cos x + 1) = 0
so
x = 0 is a solution and x = 180 is a solution
then
cos x = 1/2
that is at x = 120 and x = 240

trig  Reiny, Thursday, July 4, 2013 at 9:45pm
We should also include 360° , (from sinx = 0)
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