To determine to measure of the unknown angle, be sure to use the total sum of 180°. If two angles are given, add them together and then subtract from 180°. If two angles are the same and unknown, subtract the known angle from 180° and then divide by 2.
Total height = 1yd + 1yd+1/3yd = 2 1/3 yd = 7/3 yd
7/3 yd = 7/3 * 36 inch = 84 inch