Not looking for answer, just walk through of which double angle formula to use.

SinX=Cos2X

Question

Not looking for answer, just walk through of which double angle formula to use.

SinX=Cos2X

turingtest · Answer

the one that leaves everything in terms of sine and a constant

immings · Answer

cos^2x-sin^2x?

turingtest · Answer

no, that one has a cosine in it...

immings · Answer

oh soorry dyslexic, thought it said and cosine. so 1-2sin^2x

turingtest · Answer

yeah :)

immings · Answer

sinx / 2sin^2x = 1

1 / 2sinx = 1

turingtest · Answer

whoa there? what did you do?

turingtest · Answer

sinx=1-sin^2x

immings · Answer

moved 2sin^2 x to the right side

immings · Answer

left*

turingtest · Answer

how, by division?
if so you did the algebra wrong

immings · Answer

oh, I see. I forgot to type the negative sign

turingtest · Answer

you divided?

immings · Answer

yes

turingtest · Answer

if you divide both sides by 2sin^2x you get
cscx=csc^2x-1
that doesn't really help us...
try addition to get the everything on the left hand side

terenzreignz · Answer

Might I suggest removing confusion by replacing all instances of sin x with, say, u, to make it look more algebra-y? :)

turingtest · Answer

sorry, you would get
1/2cscx=1/2csc^2x-1

immings · Answer

That's not how it is shown from previous examples. there's no addition

turingtest · Answer

@terenzreignz  yeah I was gonna get to that when we got it =0 to show that it looks quadratic, but you could of course do it now as well :)

turingtest · Answer

@immings Previous example does not matter. all problem,s are different. I'm telling you to us addition (and subtraction) to get everything on the left hand side

immings · Answer

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