作CD⊥AB,垂足D,
∠BAC=30°=∠BCD,
BC=AB/2=2R/2=R;
BD=BC/2=R/2,
CD²=BC²-BD²=R²-R²/4
CD=√3R/2;
AC=2CD=√3R;
集合体由两个圆锥组成,
表面积=两个圆锥的侧面积
=2πCD*AC/2+2πCD*BC/2
=2π*(√3R/2)*(√3R+R)/2
=π(3+√3)R²/2.
作CD⊥AB,垂足D,
∠BAC=30°=∠BCD,
BC=AB/2=2R/2=R;
BD=BC/2=R/2,
CD²=BC²-BD²=R²-R²/4
CD=√3R/2;
AC=2CD=√3R;
集合体由两个圆锥组成,
表面积=两个圆锥的侧面积
=2πCD*AC/2+2πCD*BC/2
=2π*(√3R/2)*(√3R+R)/2
=π(3+√3)R²/2.