tg a = 4/3, a€[-π; -π/2] (3 четверть триганометра)
ctg a = 1/tga = 3/4
1+ctg²a = 1/sin²a
sin²a = 1/1+ctg²a =1/(1+9/16) = 16/25
sin a = -4/5
tg a = 4/3, a€[-π; -π/2] (3 четверть триганометра)
ctg a = 1/tga = 3/4
1+ctg²a = 1/sin²a
sin²a = 1/1+ctg²a =1/(1+9/16) = 16/25
sin a = -4/5