document.write( "Question 535678: Verify the reduction formula:
\n" ); document.write( "a) sin(x - 5pi/2)= -cosx\r
\n" ); document.write( "\n" ); document.write( "b) sin(x+ pi)= -sinx \n" ); document.write( "
Algebra.Com's Answer #351995 by lwsshak3(11628)\"\" \"About 
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Verify the reduction formula:
\n" ); document.write( "a) sin(x - 5pi/2)= -cosx
\n" ); document.write( "use sin addition formula
\n" ); document.write( "sin(s-t)=sin s cos t-cos s sin t
\n" ); document.write( "sin(x-5π/2)=sinxcos5π/2-sin5π/2cosx
\n" ); document.write( "reference angle for 5π/2=π/2
\n" ); document.write( "cos(5π/2)=cos(π/2)=0
\n" ); document.write( "sin(5π/2)=sin(π/2)=1
\n" ); document.write( "sin(x-5π/2)=sinxcos5π/2-sin5π/2cosx
\n" ); document.write( "sin(x-5π/2)=0-cosx=-cosx
\n" ); document.write( "..
\n" ); document.write( "b) sin(x+ pi)= -sinx
\n" ); document.write( "sin(s+t)=sin s cos t+cos s sin t
\n" ); document.write( "sin(x+π)=sinxcosπ+cosxsinπ
\n" ); document.write( "cos(π)=-1
\n" ); document.write( "sin(π)=0
\n" ); document.write( "sin(x+π)=sinx*(-1)+cosx*0
\n" ); document.write( "sin(x+π)=-sinx
\n" ); document.write( "verified: left side=right side \n" ); document.write( "
\n" );