In this right triangle and we are given the leg opposite (13 cm) and adjacent (4cm)to the angle.
SOHCAH(TOA)
^this tells us that tanθ=Opposite/Adjacent
tanθ=13/4
*to solve for the angle we need to use inverse tangent
θ= tan^-1(13/4)
Now just put the right side into a calculator (make sure you are in degrees mode!!)
θ=72.9°