Posted by **bob** on Wednesday, March 16, 2011 at 5:01pm.

for sin2x+cosx=0, use double-angle or half-angle formula to simplify the equation and then find all solutions of the equation in the interval (0,2Pie)

- Trig?? -
**Writeacher**, Wednesday, March 16, 2011 at 5:23pm
Please type your __subject__ in the **School Subject** box. Any other words, __including obscure abbreviations__, are likely to delay responses from a teacher who knows that subject well.

- trip -
**bobpursley**, Wednesday, March 16, 2011 at 5:58pm
sin2x= 2sinxcosx

cosx(2sinx+1)=0

cosx=0 so x=0, PI, 2PI

sinx=-1/2, so x=3PI/2 check that.

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