document.write( "Question 1074684: Marty is proving that the following trigonometric identity is true:\r
\n" ); document.write( "\n" ); document.write( "tan^2θ⋅cos^2θ=1−cos^2θ\r
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\n" ); document.write( "\n" ); document.write( "Which step would be the first line of his proof?\r
\n" ); document.write( "\n" ); document.write( "tan^2θ⋅cos^2θ=1−sin^2θ\r
\n" ); document.write( "\n" ); document.write( "tan^2θ⋅cos^2θ=tan^2θ\r
\n" ); document.write( "\n" ); document.write( "tan^2θ⋅cos^2θ=sin^2θ\r
\n" ); document.write( "\n" ); document.write( "tan^2θ=1−cos^2θ⋅cos^2θ
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Algebra.Com's Answer #689335 by Alan3354(69443)\"\" \"About 
You can put this solution on YOUR website!
I would add cos^2 to each side,
\n" ); document.write( "--> tan^2 = 1
\n" ); document.write( "Not an identity.
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\n" ); document.write( "And, I would use parentheses.
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