Elements of plane and spherical trigonometry (1833)
Young, J. R. (John Radford), 1799-1885 · Philadelphia, Carey, Lea & Blanchard · leaf 132
writers on sphericalsubjects, and even to the present day, not more than three of their pro-perties have, we believe, been published. 2. Let O be the centre of the circle in-scribed in the fundamental triangle, and G,H, K, its points of contact with the sides, joinAO, BO, CO, and draw the radii to… … + /? + ^ = y = a-\-b-\- c 2— a-\-b-\- c 2a — b -\- c 3 a-\-b — c (1). Again, in the right-angled triangle BOG, we havetan. OG = sin. BG tan. OBG, that is, tan. r = sin. 0 tan. § B; or by (1)just given and (3), upon page 49, applied to B, we have tan. r sin. 5 — * sm — a sm.s sin. s 5 — -b _V ^sin.…
