The - - 4X + g tangential area may be expressed in terms of chordal areas.
If we write CI for the chordal area obtained by taking ordinates at intervals Zh, then T i =2CI-C I.
Some of the formulae obtained by the above methods can be expressed more simply in terms of chordal or tangential areas taken in various ways.
2um) Now, if p is any factor of m, there is a series of equidistant ordinates uo, up, 142p, um - p, um; and the chordal area as determined by these ordinates is ph (2uo + up + u2p +.
The following are some examples of formulae of this kind, in terms of chordal areas.