Ctg (arcsin1 - arcctg 2) = ?

решите с объяснениями!

Ctq (arcsin1 - arcctq2) - ?---

arcsin1 = π/2; arcctq2 = α.

ctqα = 2 ⇒tqα = 1/ctqα = 1/2.

ctq (arcsin1 - arcctq2) = ctq (π/2 - α) = tqα ||по формуле приведения ||

=tq (arcctq2) = tq (arctq (1/2)) = 1/2.