Question 904452
{{{1/cos(y) = 13/5}}}, cos(y) = 5/13  and sin(y) = 12/13 {{{12 = sqrt(169-25)}}}
sin(x) = 4/5, cos(x) = 3/5 {{{3 = sqrt(25-16)}}}
sin(x+y) = sin(x)c0s(y)+ cos(x)sin(y) = {{{(4/5)(5/13) + (3/5)(12/13) = 56/65}}}