Question 1064902
{{{tan(A)=5=5/1=sin(A)/cos(A)}}}
so,
{{{sin(A)=-5/sqrt(5^2+1^2)=-5/sqrt(26)=-(5/26)sqrt(26)}}}

{{{cos(A)=-1/sqrt(26)=-sqrt(26)/26}}}
and
{{{sin(B)=2/3}}}
{{{cos(B)=-sqrt(1-(2/3)^2)=-sqrt(1-4/9)=-sqrt(5/9)=-sqrt(5)/3}}}
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Now use the formula,
{{{cos(A-B)=cos(A)cos(B)+sin(A)sin(B)}}}