h В h h В t P+ 45° 45° B-B section

In the shown diagram below, the curved out bar has an axis that is circular (with mean radius r = 12in) and is subjected to the m horizontal forces P = 400lb at the two ends. The cross-section of the bar is a triangular shape with height h and thickness t.

If the allowable tensile stress in the bar is 12,000 psi, and height h=1.2 in, what's the minimum thickness tmin that is required?