document.write( "Question 373748: Can you please help me to prove a tangent subtraction identity tan(a-b)=(tana-tanb)/(1+tana*tanb) using geometric techniques?\r
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Algebra.Com's Answer #265977 by solver91311(24713) $\"\"$ $\"About$

You can put this solution on YOUR website!
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\n" ); document.write( "\n" ); document.write( "I don't know of a direct geometric proof of the tangent of a difference formula. I've always seen it done by geometric proofs of

and

and then using

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\n" ); document.write( "\n" ); document.write( "Geometric proofs of the sine and cosine of differences can be found at:\r
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\n" ); document.write( "\n" ); document.write( "Sine and Cosine of Difference Proofs\r
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\n" ); document.write( "\n" ); document.write( "Then the algebra to get it into the final form for tangent is found at:\r
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\n" ); document.write( "\n" ); document.write( "Sum/Difference Formulas (Scroll Down to TANGENT A±B)\r
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\n" ); document.write( "\n" ); document.write( "John
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\n" ); document.write( "My calculator said it, I believe it, that settles it
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