Question 836065
Prove the following identities:
Cos^4 A + sin^4 A + 2sin^2 Ax cos^2 A =1
Factor:
(cos^2+sin^2)(cos^2+sin^2) = 1
1*1 = 1
1 = 1
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CosA -sinA/ cos A+sinA = 1-2sinAcosA/1-2sin^2A
Left side: Multiply numerator and denominator by cos-sin
Right side: In place of "1" put sin^2+cos^2
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(cos-sin)^2/(cos^2-sin^2) = [sin^2 -2sin*cos +cos^2]/(1-2sin^2)
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Notice that the numerators are the same
Notice that the denominators are the same
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(cos^2-2cos*sin+sin^2)/(1-2sin^2) = (cos^2-2sin*cos+sin^2)/(1-2sin^2
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Cheers,
Stan H.
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