# Math Help - Sinus equation

1. ## Sinus equation

Hello again.

I´m stuck again..

How do i solve:

$sin(2y)=0.5$

should i make it in a form of

$y= sin...$??

Best Regards

2. Originally Posted by DenOnde
Hello again.

I´m stuck again..

How do i solve:

$sin(2y)=0.5$

should i make it in a form of

$y= sin...$??

Best Regards
$2y = \frac{\pi}{6} + 2n \pi$ or $2y = \frac{5\pi}{6} + 2n \pi$ where $n \in Z$. Therefore ....

3. so i should take

$y = (\pi/6)+n*\pi/2$ ?

thank you for the quick reply btw

4. Originally Posted by DenOnde
so i should take

$y = (\pi/6)+n*\pi/2$ ?

thank you for the quick reply btw
No.

You have not correctly divided by 2 both sides of the two general solutions I set up.

5. But i don't really understand where the other solution come from?

6. Originally Posted by DenOnde
But i don't really understand where the other solution come from?
Draw a unit circle. Then see that the sine of an angle is positive in quadrant 1 and quadrant 2.

7. ah.... of course... if you have it in degrees it's equal to 180-30 therefor the second solution?

so next i should divide both solutions by 2?