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anonymous
 5 years ago
Not sure the right approach to solve the identity:
tan3x  tanx = 2sinxsecx
anonymous
 5 years ago
Not sure the right approach to solve the identity: tan3x  tanx = 2sinxsecx

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Owlfred
 5 years ago
Best ResponseYou've already chosen the best response.1Hoot! You just asked your first question! Hang tight while I find people to answer it for you. You can thank people who give you good answers by clicking the 'Good Answer' button on the right!

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0sorry i meant tan3x  tanx = 2sinxsec3x

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0this is a tricky  you might try converting to functions of sin and cos

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0i've spent a lot of time trying diff techniques, splitting 3x in sinx and cosx components but am getting no where fast!

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0yeah  i've got a headache trying this one but I've got to go out now. I'll look at it later. Maybe someone else can help meantime. I'd like to see the proof of this one. Meanwhile  the best of luck.

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0ok steanson  I've got it first convert to sin and cos: sin3x/cos3x six/cosx this can be written as (sin3xcosx  sinxcos3x) / cos3xcosx by the 'sums and differences of trig ratios formulae: the numerator = 1/2(sin4x +sin2x)  1/2(sin4x sin2x) which reduces to sin2x which we can write as 2sinxcosx sowe have: 2 sinxcosx/cos3xcosx cancelling out cosx = 2sinx/cos3x =2sinxsec3x

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0the rules i referred to are sinx + siny = 2sin[(x+y/2][cos(xy)/2] and sinx  siny = 2cos[(x+y/2][sin(xy)/2] and I used them from' right to left' A good way to remember these is eg the first one 'sinx + siny = 2 sin semi sum cos semi difference' there are similar rules for the sum of differences of cosines. A higher grade maths book should have them

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0thanks very much!, i think the reason i struggled is i didn't have those sinx + siny identities given in my text, handy to know!
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