A ramp that is 3.25m long leads up to a platform which is 1.25m high. A cubic packing

case of side length 1m that weighs 50kg stands at the top of the ramp. It is held in position

by a rope held parallel to the ramp.

(a) If the coefficient of static friction is 0.35, what is the tension in the rope?

I am trying to understand the solution to this problem, but I don't understand the part where values of

$\displaystyle sin \theta = \frac{5}{13} $

$\displaystyle cos \theta = \frac{12}{13} $

how were these values obtained?