Question 1074123
{{{(sin(a)cos(b)+cos(a)sin(b))/(sin(a)/cos(a)+sin(b)/cos(b))}}}


{{{(sin(a)cos(b)+cos(a)sin(b))/((cos(b)sin(a)+cos(a)sin(b))/(cos(a)cos(b)))}}}


{{{((sin(a)cos(b)+cos(a)sin(b))/(cos(b)sin(a)+cos(a)sin(b)))(cos(a)cos(b))}}}


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If you look at the fraction on the left carefully, you will easily make the steps to show that it is equal to 1.
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{{{1*cos(a)cos(b)}}}





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Used angle sum identity  {{{sin(a+b)=sin(a)cos(b)+cos(a)sin(b)}}}