点A，B，C都在半径为r的圆上，直线AD⊥直线BC，垂足为D，直线BE⊥直线AC，垂足为E，直线AD与BE相交于点H．若BH= 3 AC，则∠ABC所对的弧长等于_1（长度单位）．

题干

点A，B，C都在半径为r的圆上，直线AD⊥直线BC，垂足为D，直线BE⊥直线AC，垂足为E，直线AD与BE相交于点H．若BH= 3 AC，则∠ABC所对的弧长等于____（长度单位）．

上一题下一题 0.0难度选择题更新时间:2012-09-12 03:26:55

\frac{1}{3}

\u03c0r\u6216

\frac{5}{3}

Indoor Water Park
Opening time	◆9: 00a.m.--6:00p.m. from Monday to Friday◆8: 00a.m.- 10: 00p.m. from Saturday to Sunday
Ticket price	◆Adults: 150 yuan/person: 130 yuan/member◆Children: above 1.2 meters, 75 yuan/person; 60 yuan/member under 1.2 meters. free
Should not take	food, pets, knives, rings
Things to remember	◆Children under 1. 4 meters and old people above 60 should stay with other adults◆You should follow the rules in the water park.◆If you have some health problems and aren't suitable for water activities, you'd better not come in