6 (§ 34) we draw ordinates QD midway between KA and MC, and RE midway between MC and LB, meeting the top in D and E (fig.

If we were to take QD and RE closer to MC, the former area would be still greater.

1-(QD + RE).

If QD is the bounding ordinate of one of the component strips, we can calculate the area of Qdbl in the ordinary way.

The data for the area ADQ are a series of values of u corresponding to equidifferent values of x; if we denote by y the distance of a point on the arc AD from QD, we can from the series of values of u construct a series of values of y corresponding to equidifferent values of u, and thus find the area of ADQ, treating QD as the base.