1.原式=3√10(√2/2*sinx+√2/2cosx)
=3√10(sinxcosπ/4+cosxsinπ/4)
=3√10sin(x+π/4)
2.2分之3cosx-2分之跟号3sinx
=根号3(根号3/2osx-1/2sinx)=根号3（sin60度*cosx-cos60度*sinx）
=根号3sin(60度-x)