Saturday

October 25, 2014

October 25, 2014

Posted by **Hannah** on Thursday, February 18, 2010 at 2:59pm.

sin 2x = -sqrt3/2

I know that the angles are 4pi/3 and 5pi/3 and then since it is sin I add 2npi to them.

2x = 4pi/6 + 2npi 2x = 5pi/3 + 2npi

Now I know that I have to divide by 2 but that is where I an not sure.

x = 4pi/6 + npi x=10pi/3 + npi

Is that correct???

- Pre-Cal(Please check) -
**Reiny**, Thursday, February 18, 2010 at 5:07pmHere is how I do these:

sin 2x = -√3/2

so by the CAST rule, 2x must be in quadrants III or IV

The angle in standard position (ignore the negative) is pi/3

so for III, 2x = pi + pi/3 = 4pi/3

for IV, 2x = 2pi - pi/3 + 5pi/3, you had both of those correct

Then x = 2pi/3 and 5pi/6

the period of sin 2x is pi, so adding/subtracting multiples pi to our two angles will yield more angles

since your domain is (0,2pi)

other solutions for x are 2pi/3 + pi = 5pi/3

and 5pi/6 + pi = 11pi/6

so x = 2pi/3, 5pi/3, 5pi/6 and 11pi/6

we would have

**Answer this Question**

**Related Questions**

Pre-Cal(Please check) - 1) Find all the solutions of the equation in the ...

Pre-Cal (Please help) - Find all the soultions of the equation in the interval...

Pre-Cal - Find all the soultions of the equation in the interval (0,2pi) sin 2x...

Pre-Cal(Please check) - Approximate the equation's solutions in the interval (0,...

Math - 1. On the interval [0, 2pi] what are the solutions to the equation ...

Pre-Cal - Find all the solutions of the equation in the interval (0,2pip) sin(x...

Pre-Cal(Urgent!!) - Find all the solutions of the equation in the interval (0,...

Pre-Cal(Please help) - Approximate the equation's soultions in the interval (o...

Precalculus check answers help! - 1. Which expression is equivalent to cos ...

Pre Cal. - 1. Use half-angle identity to find the exact value of cos165. MY ...