document.write( "Question 799186: establish the identity.
\n" ); document.write( "sin(θ+β)/tan(α)tan(β)= cos(α)cos(β) \n" ); document.write( "
Algebra.Com's Answer #482539 by harpazo(655)\"\" \"About 
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Use the following trig identities:\r
\n" ); document.write( "\n" ); document.write( "sin(A+B) = sin(A)cos(B) + cos(A)sin(B)\r
\n" ); document.write( "\n" ); document.write( "tan(A) = sin(A)/cos(A)\r
\n" ); document.write( "\n" ); document.write( "tan(B) = sin(B)/cos(B)\r
\n" ); document.write( "\n" ); document.write( "Substitute the above into your equation and simplify the left side to look like the right side.\r
\n" ); document.write( "\n" ); document.write( "sin (A + B) = (sin A)(cos B) + (cos A)(sin B) ; Divide both sides by (cos A)(cos B)
\n" ); document.write( "=> sin (A + B) / {(cos A)(cos B)} = (sin A)/(cos A) + (sin B)/(cos B)
\n" ); document.write( "=> sin (A + B) / {(cos A)(cos B)} = tan A + tan B
\n" ); document.write( "=> sin (A + B) / (tan A + tan B) = (cos A)(cos B)\r
\n" ); document.write( "\n" ); document.write( "Verify your question.\r
\n" ); document.write( "\n" ); document.write( "Question for you:\r
\n" ); document.write( "\n" ); document.write( " Is the denominator of LHS (tan A) + tan B) or (tan A)(tan B)? You did not make this clear in your post.\r
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