what is sinx = sin2x

And finally to end my sporadic math question spree...!

what is sinx = sin2x?

how do you solve, and what is the answer?

and i dunno, what unit do you use, radians or degrees? Does one make the question easier than the other?

Thanks again!

sin x=sin (2x)
sin x=2sin(x)cos(x); identity, based off of sin(a+b) and sin(a-b)
sin x - 2sin(x)cos(x)=0
sin(x)*(1-2cos(x))=0

First case:
1/2=cos(x); now take cos^-1, and it doesn't really matter whether you use radians or degrees - I used radians
x=pi/3

Second case:
sin(x)=0
x=0

Then, as sin is periodic, there a bunch of other solutions in the form of [solution, such as x=0]+2pi*[an integer]

again, couple questions. (I'm really weak at this stuff)

sin x - 2sin(x)cos(x)=0
sin(x)*(1-2cos(x))=0
how'd you get from first line to next?

secondly, you get from (1-2cos(x))=0 to 1/2=cos(x) by dividing 2 to both sides right?
yea, me thinks yes.

so just the first question then.

Thanks

"how'd you get from first line to next?" I factored out a sin(x). sin(x)*1 - sin(x)*2cos(x)=0

"secondly, you get from (1-2cos(x))=0 to 1/2=cos(x) by dividing 2 to both sides right?" Basically, if you add 2cos(x) to both sides and then divide by 2 that's what you get

Si, si, senior!!!

I should've known better and saw that you took sinx out

Gracias muchas!

(btw, no, i dont speak spanish)