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TbbZz
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Homework Statement
Prove that the Given Equation is an Identity:
Code:
sin2A
------ = cotA
1 - cos2A
Homework Equations
sin(A+B) = sinAcosB + cosAsinB
cos(A+B) = cosAcosB - sinAsinB
tan(A+B) = (tanA + tanB) / (1 - tanAtanB)
sin2A = 2sinAcosA
cos2A = cos[tex]^{}2[/tex]A - sin[tex]^{}2[/tex]A
tan2A = 2tanA / 1 - tan[tex]^{}2[/tex]A
The Attempt at a Solution
I tried changing sin2A to sin(A+A) and arrived at 2sinAcosA at the top.
I also tried changing 1 - cos2A to 1 - cos[tex]^{}2[/tex]A - sin[tex]^{}2[/tex]A, but then I arrived at having a 0 in the denominator.
I'm really not sure where to start in trying to prove the identity. I understand that I should not touch the cotA on the right hand side, but no matter what I do to rewrite the left side I can't seem to arrive at the cotA.
I would appreciate it if someone could point me in the right direction. Thank you in advance for the assistance.