Question 1163852
{{{cos(u-v)=cos u*cosv+sinu*sinv}}}
{{{(sin  u)^2+(cos u)^2=1}}}
{{{(-7/25)^2+(cos u)^2=1}}}
{{{49/625+(cos u)^2=1}}}
{{{(cos u)^2=1-49/625}}}
{{{(cos u)^2=576/625}}}
{{{u}}} is in Quadrant III, therefore {{{cos u=-sqrt(576/625)}}}
{{{cos u=-24/25}}}
{{{(sin  v)^2+(cos v)^2=1}}}
{{{(sin  v)^2+(-4/5)^2=1}}}
{{{(sin  v)^2+16/25=1}}}
{{{(sin v)^2=1-16/25}}}
{{{(sin v)^2=9/25}}}
{{{v}}} is in Quadrant III, therefore {{{sin v=-sqrt(9/25)}}}
{{{sin v=-3/5}}}
{{{cos(u-v)=-24/25*(-4/5)+(-7/25)*(-3/5)=96/125+21/125=117/125}}}