The cross-section of a cannel is a trapezium in shape. If the cannel is 9 m wide at the top and 7 m wide at the bottom and the area of cross-section is 560 sq m, the depth of cannel is? Select.
A) 39	B) 28	C) 70	D) 80	E) 71
1/2 * d (9 + 7) = 560   d = 70   Answer: 70
<result>C</result>
The cross-section of a cannel is a trapezium in shape. If the cannel is 9 m wide at the top and 7 m wide at the bottom and the area of cross-section is 560 sq m, the depth of cannel is?