[질문] 배각공식즘알려주세요

배각공식 sin(2a) = 2sin(a)cos(a) cos(2a) = cos(a)^2 - sin(a)^2 = 2cos(a)^2 - 1 = 1 - 2sin(a)^2 tan(2a) = 2tan(a)/{1-tan(a)^2}