A maths question Watch

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superkillball
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#1
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Prove that

cosec2X+cot2X=cotX

How to prove it?
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gzftan
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(Original post by superkillball)
Prove that

cosec2X+cot2X=cotX

How to prove it?
Erm...this is P2 for me from last year....try using the double angle formulae for cosec2x (1/sin2x) and cot2x (1/tan2x)....then see if they cancel to give 1/tanx??

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Ralfskini
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LHS = cosec2x + cot2x = 1/sin2x + cos2x/sin2x = (1 + cos2x)/sin2x = 2(1 - sin^2x)/2sinxcosx = 2cos^2x/2sinxcosx = cosx/sinx = cotx = RHS.
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gzftan
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(Original post by Ralfskini)
LHS = cosec2x + cot2x = 1/sin2x + cos2x/sin2x = (1 + cos2x)/sin2x = 2(1 - sin^2x)/2sinxcosx = 2cos^2x/2sinxcosx = cosx/sinx = cotx = RHS.
Yeh...that's what i was thinking....

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superkillball
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thank you
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