Răspuns:
∡ANM = ∡ACB + 1/2∡BAC = ∡ACB + 1/2(180 - ∡ABC -∡ACB) = 1/2∡ACB - 1/2∡ABC + 90
∡MAN = 90 - ∡ANM = 1/2∡ABC - 1/2∡ACB = 1/2(∡ABC - ∡ACB)