The points R, T, and U lie on a circle that has radius 4. If the length of arc RTU is 4PI/3ATH connecttype="rect" gradientshapeok="t" extrusionok="f">ATH>, what is the length of line segment RU?
A.4/3
B.8/3
C. 3
D. 4
E. 6
答案是D
但是我觉得如果RU为4的话，那么arcRTU应该是5Pi/3
大家看看我错在哪里了 | 
