The versine, coversine, haversine, and exsecant were used in navigation. Noting that , the haversine formula immediately follows. The term "haversine" was coined in 1835 by James Inman. Some of these methods were H.O. 211 (Ageton), Davies, haversine, etc. Since the haversine formula uses sines, it avoids that problem. There are several related functions, most notably the coversine and haversine. The haversine function computes half a versine of the angle . The latter, half a versine, is of particular importance in the haversine formula of navigation.