Third proportional 'c' to 'a' and 'b' is b²/a. c = (12 * 12) / 9 = 144 / 9 = 16.
तृतीयानुपाती 'c' का सूत्र b²/a है। c = (12 * 12) / 9 = 144 / 9 = 16।