PS中的兩道幾何（新東方藍書上冊）

gmathan

116。The polints R,T,U lie on a circle that has radius 4. If the length of arc RTU is 4派/3，what is the length of line segment RU?（無圖）

126.In the figure above, two rectangles with the same dimensions overlap to form the shaded region. If each rectangle has perimeter 12 and the shaded region has perimeter 3, what is the total length of the heavy line segments?(figure 就是兩個長方形有點重疊，重疊部分是一個陰影三角形)。關鍵是不懂 Heavy line segments 的意思