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# Trigonometric equation question

Mon 17 Sep, 2012 11:08 am
given: sinx=t, 90<x<180
express the equation sin2x+tgx using "t" (begin by expressing cosx using t)

I've begun the problem using tan=sin\cos... not really getting anywhere with it. Could use some help! Thanks!
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Type: Question • Score: 1 • Views: 716 • Replies: 3
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fresco

1
Mon 17 Sep, 2012 11:25 am
@shirkay,
use
cos =sqrt (1-sin^2)
so
cosx=sqrt (1-t^2)
and
sin2 = 1-2sin^2
so
sin 2x =1-2t^2
shirkay

1
Wed 19 Sep, 2012 07:51 am
@fresco,
ok that much I understand, thank you. The final answer is (2t^2-3)t/2ndsqrt(1-t^2)... I am not getting this answer and how does the "g" disappear?
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fresco

1
Wed 19 Sep, 2012 08:49 am
@shirkay,
Can't help you there since g is undefined. Also I see no "equation" only an "expression".
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