Elements of plane and spherical trigonometry (1833)
Young, J. R. (John Radford), 1799-1885 · Philadelphia, Carey, Lea & Blanchard · leaf 127
moment that the centre is at O^ notin the circle ZM ; and draw the perpendicular OK. Now, we haveseen that OK bisects AB in K when O is the centre, or that AK -f-KK = BK —KK; But, by hypothesis, AK = BK, and therefore, sub-tracting the latter equation, KK = — KK, which is only true whenK, K… … 4. If two great circles which cut oneanother at A, be intersected by a circle of thesphere in D, E, and H, L respectively, therectangles of the tangents of the semi-seg-ments into which they are divided shall beequal. That is,tan. i AE tan. | AD = tan. ^ AH tan. i AL. For find the centre G, draw AG…
