## anonymous 3 years ago prove THAT sin3x=cos3x

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1. .Sam.

Start by $\sin(3x)=\sin(2x+x)$ Then use the sum to difference formula

2. anonymous

are there any values setfor this question? sin 3x = cos 3x only when tan 3x =1

3. anonymous

4. anonymous

5. anonymous

oh. okay. sub x=0 into the eq and see what u get

6. anonymous

X is a angle not a variable

7. anonymous

In this case, since the question is asking for the [[proof]], not the solution, i don't see how you can get it, without setting the angles into set angles, like $$\frac{\pi}{12}$$ rad

8. anonymous

i can give you a hint..!

9. anonymous

in the case where you need the solution, sin 3x = sin (90-3x) and use the general formula, $$3x=n\pi + (-1)^n (90-3x)$$

10. anonymous

that is the solution, not the proof though. So i don't think I gave any help into solving that question. note: $$n \in N$$

11. anonymous

u wanna calculate the value of x ?

12. anonymous

just find the vale of "X"

13. anonymous

sin 45 = cos 45 sin(3*15) = cos(3*15) so x=15 thus sin3x=cos3x your welcome

14. anonymous

thanks