Question

Докажите тождество: cos a + ctg a = 1 + sin a . Под cos a + ctg a: линия дроби ctga

Answer 1

$frac{cos alpha + ctg alpha }{ctg alpha } = frac{cos alpha }{ctg alpha } +1 = cos alpha * tg alpha +1 = cos alpha * frac{sin alpha }{cos alpha } +1 = sin alpha + 1$