<PRE><B>Question 595498</B>
sin^2 + cos^2 = 1


(5/13)^2 + cos^2  = 1


25/169 + cos^2 = 1


cos^2 = 1 - 25/169


cos^2 = 144/169


cos = sqrt(144/169)


cos = 12/13


So cos(t) = 12/13</PRE>