SOLUTION: How do I answer step by step the identity 1/2 cot x/2 - 1/2 tan x/2 = cot x. I have spent several hours working on this problem and I can't figure it out.
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Question 664860: How do I answer step by step the identity 1/2 cot x/2 - 1/2 tan x/2 = cot x. I have spent several hours working on this problem and I can't figure it out. Answer by lwsshak3(11628) (Show Source):
You can put this solution on YOUR website! How do I answer step by step the identity 1/2 cot x/2 - 1/2 tan x/2 = cot x.
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Identity:tan (x/2)=(sin x)/(1+cos x)
cot (x/2)=1/tan (x/2)=(1+cos x)/(sin x)
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1/2 cot x/2 - 1/2 tan x/2 = cot x
start with left side:
1/2 cot x/2 - 1/2 tan x/2
=(1+cos x)/2(sin x)-(sin x)/2(1+cos x)
LCD: 2sin x(1+cos x)
=(1+cos x)^2-sin^2x)/(2sin x(1+cos x)
=(1+2cos x+cos^2x-sin^2x)/(2sin x(1+cos x)
1-sin^2x=cos^2x
=(2cos x+2cos^2x)/(2sin x(1+cos x)
=(cos x+cos^2x)/(sin x(1+cos x)
=(cos x(1+cos x)/(sin x(1+cos x)
=cos x/sin x
=cot x
verified: left side=right side
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