The trig function that links the side opposite the angle x and the length of the shadow is the tangent function.
Here, tan x = (opposite side) / (adjacent side) = (10 m) / (17.3 m), or 0.578.
Starting from tan x = 0.578, use the inverse tangent function to find the angle, first in radians and then in degrees:
arctan 0.578 = 0.524 radians
Converting this to degrees yields 30.03 degrees. This is the angle of elevation of the sun from the horizontal, from the point where the observer is standing.
