Question

Вычислить: а) 1 - 2sin^2 pi/8 б) 2cos^2 pi/12 - 1

Answer 1

A)1-2sin²π/8=1-2(1-cosπ/4)/2=1-1+cosπ/4=√2/2
b)2cos²π/12 -1=2(1+cosπ/6)/2 -1=1+cosπ/6-1=1/2