30tg3* tg87- 43 = 30 * tg87/ctg3 - 43 = 30 * tg87/ ctg(90 - 3) - 43 = 30 * tg87/tg87 - 43 = 30 - 43 = - 13
30tg3* tg87- 43 = 30 * tg87/ctg3 - 43 = 30 * tg87/ ctg(90 - 3) - 43 = 30 * tg87/tg87 - 43 = 30 - 43 = - 13