2sin^2x/tg2xtgx=cos^2x-sin^2x

Все формулы по тригонометрииОсновные тригонометрические тождества

sin2x + cos2x = 1

tgx = sinx cosx ctgx = cosx sinx

tgx ctgx = 1

tg2x + 1 = 1 cos2x ctg2x + 1 = 1 sin2x Формулы двойного аргумента

sin2x = 2sinx cosx

sin 2x1 = 2tgx = 2ctgx = 2 1 + tg2x 1 + ctg2x tgx + ctgx

cos2x = cos2x - sin2x = 2cos2x - 1 = 1 - 2sin2x

cos 2x1 = 1 - tg2x = ctg2x - 1 = ctgx - tgx 1 + tg2x ctg2x + 1 ctgx + tgx tg2x = 2tgx = 2ctgx = 2 1 - tg2x ctg2x - 1 ctgx - tgx ctg2x = ctg2x - 1 = ctgx - tgx 2ctgx 2