Question

упростите выражение cos a- sin a* ctg a​

Answer 1

cos(a) - sin(a)•ctg(a) = cos(a) - sin(a)•cos(a)/sin(a) = cos(a) - cos(a) = 0

Answer 2

cos a - sin a * ctg a = cos a - sin a / tan a = cos a - sin² a / sin a = cos a/sin a - sin a/sin a = tg a - sin a / sin a = tg a - 1