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You can put this solution on YOUR website!
hat is the exact value of sin2x, cos2x and tan2x if tanx=1/2,pi
\n" ); document.write( "hypotenuse of working right triangle=√(1^2+2^2)=√5
\n" ); document.write( "sinx=1/√5
\n" ); document.write( "cosx=2/√5
\n" ); document.write( "..
\n" ); document.write( "sin2x=2sinxcosx=2*1/√5*2/√5=4/5
\n" ); document.write( "cos2x=cos^2x-sin^2x=4/5-1/5=3/5
\n" ); document.write( "tan2x=sin2x/cos2x=4/3
\n" ); document.write( "check:
\n" ); document.write( "tanx=1/2
\n" ); document.write( "x=26.565˚
\n" ); document.write( "2x=53.13˚
\n" ); document.write( "..
\n" ); document.write( "sin2x=sin53.13≈0.7999...
\n" ); document.write( "exact value=4/5=0.8000
\n" ); document.write( "..
\n" ); document.write( "cos2x=cos53.13≈0.6000
\n" ); document.write( "exact value=3/5=0.6000
\n" ); document.write( "..
\n" ); document.write( "tan2x=tan53.13≈1.3333...
\n" ); document.write( "exact value=4/3≈1.3333...