A=180°-45°-105°=30°
根据正弦定理,得 a/sinA=b/sinB=c/sinC
从而 b=a*sinB/sinA
=5*sin45°/sin30°
=5*√2/2/(1/2)
=5√2
c=a*sinC/sinA
=5*sin105°/sin30°
=5*sin75°/sin30°
=5*sin(45°+30°)/sin30°
=5*(sin45°*cos30°+cos45°*sin30°)/(1/2)
=5*(√2/2*√3/2+√2/2*1/2)*2
=5*(√6/2+√2/2)
=5*(√6+√2)/2