How do you verify sin2x * cotx = 1 ?

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sin2x * cotx = 1

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Answer 1 · 2017-04-07T00:41:09

You don't

Using the sine double angle formula #sin(2x)=2sinxcosx#,
#sin(2x)*cotx=2sinxcosx*cotx#.

Knowing that #cotx=cosx/sinx#,
#2sinxcosx*cotx=2sinxcosx*cosx/sinx#

Simplifying this,
#2sinxcosx*cosx/sinx=2cos^2x# which does not necessarily equal #1#