document.write( "Question 194509: I do not get how to prove that left side is equal to right side:\r
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Algebra.Com's Answer #145942 by RAY100(1637) $\"\"$ $\"About$

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tan^2a -sin^2a = sin^2a * tan^2a,,,,let a = theta
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\n" ); document.write( "but tan = sin / cos
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\n" ); document.write( "sin^2 a/cos^2a -sin^2a = sin^2a *tan^2a
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\n" ); document.write( "remember cos^2 = sin^2 =1,,, cos^2a = 1=sin^2a
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\n" ); document.write( "sin^2a / ( 1-sin^2a) - sin^2a = sin^2a * tan^2a
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\n" ); document.write( "using lcd = (1-sin^2a)
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\n" ); document.write( "( sin^2a -sin^2a (1-sin^2a) )/ (1-sin^2a) = sin^2a *tan^2a
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\n" ); document.write( "( sin^2a -sin^2a +sin4a ) (1-sin^2a) = sin^2a * tan^2a
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\n" ); document.write( "but cos^2a = 1 - sin^2a
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\n" ); document.write( " sin^4a / cos^2a = sin^2a * tan^2a
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\n" ); document.write( " with tan = sin / cos
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\n" ); document.write( "sin^2a * tan^2a = sin^2a * tan^2a \n" ); document.write( "

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