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Maths A level - Trignometric proof

Hi could someone please help (give me hints) on how to prove
tan alpha - 1/tan alpha = -2/tan2alpha
Original post by Lebkuchen
Hi could someone please help (give me hints) on how to prove
tan alpha - 1/tan alpha = -2/tan2alpha

General tips:

write out all of the trig identities on one side of the page

where there is a denominator for one term, make sure you have the same denominator for all terms on one side of the equation

1 can be substituted for any of the trig identities with some arrangements; pick the one that makes the most sense

Reply 2
you can write tan2α

by typing tan{sup}2{/sup}α

but replace the curly brackets with square ones....
Reply 3
Original post by Lebkuchen
Hi could someone please help (give me hints) on how to prove
tan alpha - 1/tan alpha = -2/tan2alpha

A good set of tips along the same lines as MindMax is at
https://www.tuitionmath.com/single-post/2016/12/09/11-tips-to-conquer-trigonometry-proving
Here, youve obv got to involve the double angle formula for tan, and based on the priciple that its easier to simplify, Id expand the right hand side and show its equal to the left. Should be a couple of lines.
(edited 2 months ago)

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