This could be a right triangle.
With the help of trigonometry, the "ratio of altitude and base" is commonly known the tangent. So
tan θ = 4/3
θ = arctan 4/3 = 53.13
We know that right triangle always has a 90 degrees. We know also that the sum of a triangle is 180.
Finding the last angle,
180 = 90 + 53.13 + x
x = 36.87
So the angle are 90, 36.87 and 53.13.