sinX+cosX=\(\sqrt{\quad}\)2(1/\(\sqrt{\quad}\)2sinX+1/\(\sqrt{\quad}\)2cosX)
=\(\sqrt{\quad}\)2(sinXcos45°+cosXsin45°）
=\(\sqrt{\quad}\)2sin(X+45°)=\(\sqrt{\quad}\)2sin60°
=\(\sqrt{\quad}\)\(\frac{6}{2}\)
一般に
AsinX+BcosX=\(\sqrt{\quad}\)(\(A^{2}\)+\(B^{2}\))sin(X+α)
ただし　cosα=A/\(\sqrt{\quad}\)(\(A^{2}\)+\(B^{2}\))　sinα=B/\(\sqrt{\quad}\)(\(A^{2}\)+\(B^{2}\))