When we have a right triangle with sides and angles, we use basic trigononemetry. Since we know the vertical leg (height of ramp) and horizontal leg (base length of ramp), we use the inverse tangent function to find the angle.
θ = tan-1(height of ramp / base of ramp) θ = tan-1(2.5 / 6) θ = tan-1(5 / 12)