Question

Найдите значение выражения arccos( 1cos 3π /4)

Answer 1

arccos(1cos3pi /4) = arccos(sqrt{2} /2) = pi /4

Answer 2

arccos(cos(π-π/4)) = arccos(-cos π/4)) = π - arccos(cos π/4) = π - arccos(√2/2) = π - π/4 = 3π4