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# Solving trig equations watch

1. I have sin(2theta) = 1/2 which I’m supposed to solve in the domain -pi to pi. My question is for the 3rd and 4th solution, why do you do pi/6 - pi and 5pi/6 - pi instead of + pi?
2. This is what I got hope this is helpful.
3. (Original post by Howie_2114)
This is what I got hope this is helpful.
There’s supposed to be 4 solutions apparently in the domain -pi to pi, which is what confuses me, as the markscheme says that the 3rd and 4 solution is -7pi/12 and -11pi/12
4. what you do is expand the domain for sin(a)=1/2 from -2pi to 2pi
Find the solutions for a=pi/6, 5pi/6, -7pi/6 and -11pi/6

Then divide by 2 every answer to find theta.
5. (Original post by tremen222)
what you do is expand the domain for sin(a)=1/2 from -2pi to 2pi
Find the solutions for a=pi/6, 5pi/6, -7pi/6 and -11pi/6

Then divide by 2 every answer to find theta.
thank you mate, makes so much more sense now

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