HELP PLEASE! METAL.
Find all solutions to the equation.

sin2x + sin x = 0

Question

HELP PLEASE! METAL.
Find all solutions to the equation.

sin2x + sin x = 0

anonymous · Answer

sin 2x + sin x = 0
2.sin x.cos x + sin x = 0
sin x(2 cos x + 1) = 0
2 cos x + 1 = 0
cos x = -1/2
x = 120 degrees

anonymous · Answer

How did you get that Answer?

directrix · Answer

Is the solution set supposed to come from the set of all real numbers?
Did the instructions mention that?

anonymous · Answer

Yes.

anonymous · Answer

when no, but I assume so.

directrix · Answer

At this point in the work above, the Zero Product Property should have been used.

sin x(2 cos x + 1) = 0

sinx x = 0  Or  cos x + 1 = 0
 
sin x = 0   Or   cos x = -1


@lalithavasanth

anonymous · Answer

That's it?

anonymous · Answer

but cos x should be equal to -1/2...?

anonymous · Answer

Is that it?

directrix · Answer

@clairvoyant1 

What does this mean in your text?

>>Find all solutions to the equation.

We need to know over what domain we are solving the equation.

anonymous · Answer

sin squared of x + sin x = 0 ?

directrix · Answer

And, we need to know if by sin2x + sin x = 0 , you meant to convey:
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