Show that the moment of inertia for the area of any regular polygon is a constant with respect to all axes in the plane of the area which pass through its centroid. 856. Show that the moment of inertia for the area of a quarter circle with respect to its axis of symmetry is (-2) where r is the radius. 16 857. The figure for Prob. 825 is redrawn as shown in Fig. P-857. Check the answer to Prob. 825 (i.e., find 1) by first computing I, and I, then using Mohr's circle to find I, and finally transferring this value to the X axis. -15% - -10% X. 9-sin 8" FIG. P-858. FIG. P-857. 858. Use the idea discussed in Prob. 857 to compute the value of I, for the area shown in Fig. P-858. Ans. I, 2660 in."