^{page note 235 *} x sec ½ (B-C) in most cases gives a more accurate result a than y cosec ½ (B-C).

^{page note 235 †} Checking the larger side in most cases gives a more accurate result.

^{page note 235 ‡} Further notes to the examples:

• (i) All angles used in the evaluation are acute.

• (ii) if, as can easily happen in the tangent formula, the angles to be found get interchanged, by using ½ (B-C) in cases where it should be ½(C-B, the error is at once shown up by the check.