The illumination source S is installed above the center point O of a circular square with a radius of 27 meters. S is conical towards the ground, and the apex angle of its axial section SAB is120. Find the vertical height SO of the light source from the ground (accurate to 0. 1 m).

This problem is explained by taking the square root and cube root of junior two mathematics as an example. It's too difficult. I've tried to answer it. Give me a satisfactory answer.