根据正弦定理,有BC/sinA = AB/sinC,则有BC = AB*sinA/sinC而,AB=3+√3= (√3)(1+√3)sinA = sin60° = √3/2,sinC = sin(180°-60°-45°) = sin(30°+45°)= sin30°cos45° + cos30°sin45°= (1/2)*(√2/2) + (√...