Posted by **MATHS QUESTION!!!!!!!!!!!!!!!!!!!!!!!!!!** on Sunday, December 6, 2009 at 2:00pm.

solve algebriaclly the equation y=2sin2x+1 for 0<_x_<180. when solved find the x coordinates of the roots.

- PLEASE ANSWER MATHS!!! -
**Reiny**, Sunday, December 6, 2009 at 2:18pm
I am assuming you are trying to solve

2sin2x+1 = 0

sin 2x = -1/2

(angle in standard position is 30º)

the sine is negative in quadrants III and IV

so x = 180+30 = 210

or x = 360-x30 = 330

Btw, don't shout!

- Shouting! -
**Writeacher**, Sunday, December 6, 2009 at 2:25pm
When you type in all-caps, two things happen:

**it's harder to read, and

**it's the online equivalent to SHOUTING (considered rude behavior).

Please just type in regular mode, not with the Caps Lock feature turned on. Thanks.

- Correction -
**Reiny**, Sunday, December 6, 2009 at 2:34pm
my last couple of lines should have been

so 2x = 180+30 = 210

or 2x = 360-x30 = 330

so x = 105 or x = 165

since the period of sin 2x is 180º

two other solutions are 285º and 345º

check: 2sin(2x345) + 1 = 0

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