Please help???
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{2sinx} / {sin2xcosx}
= {2sinx} / {2sinxcosxcosx} because of the trig identity sin2x = 2sinxcosx
= 1 / (cosxcosx) cancel the 2sinx (one on top one on bottom
= 1 / cos^2 x self explanatory
= sec^2 x because secant is the reciprocal of cos
= {2sinx} / {2sinxcosxcosx} because of the trig identity sin2x = 2sinxcosx
= 1 / (cosxcosx) cancel the 2sinx (one on top one on bottom
= 1 / cos^2 x self explanatory
= sec^2 x because secant is the reciprocal of cos
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To prove identities like this, it's easiest to start with the more complex side and simplify it until you get to the other side. So, I'll start with:
2sinx/sin2xcosx
You should know that sin2x=2sinxcosx.
2sinx/2sinxcosxcosx
2sinx/2sinxcos²x
The 2sinx/2sinx cancels, leaving
1/cos²x
Since 1/cosx=secx, and 1/cos²x=1/cosx*1/cosx,
1/cos²x=secx*secx
Which equals
sec²x. The desired results ahve been achieved.
2sinx/sin2xcosx
You should know that sin2x=2sinxcosx.
2sinx/2sinxcosxcosx
2sinx/2sinxcos²x
The 2sinx/2sinx cancels, leaving
1/cos²x
Since 1/cosx=secx, and 1/cos²x=1/cosx*1/cosx,
1/cos²x=secx*secx
Which equals
sec²x. The desired results ahve been achieved.
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{2sinx} / {sin2xcosx} =
2sinx/2sinxcosxcosx =
1/cos^2(x) = sec^2(x)
2sinx/2sinxcosxcosx =
1/cos^2(x) = sec^2(x)
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{2sinx} / {sin2xcosx} = {2sinx} / {2sinxcos²x} = 1 / cos²x = sec²x. True.