[질문] 왜sinx+cosx=루트2sin(x+파이/4)죠?

sinx+cosx=√2[(1/√2)sinx+(1/√2)cosx)]=√2[sin(π/4)cosx+sinxcos(π/4)]=√2sin(x+(π/4))이죠 sinacosb+sinbcosa=sin(a+b)니까요^^