Question

3 sin (2 $alpha$ - $frac{ pi }{4}$) + 2 cos (3 $alpha$ - $pi$)

если $alpha$ = $frac{ pi }{4}$

Answer 1

... = 3*sin((2*π/4) - (π/4)) + 2*cos((3*π/4) - π) =
= 3*sin(π/4) + 2*cos(-π/4) = 3*√2 / 2 + 2*√2 / 2 = 5√2 / 2
косинус --- функция четная, т.е. cos(-x) = cos(x)