the cross - section of a cannel is a trapezium in shape . if the cannel is 6 m wide at the top and 4 m wide at the bottom and the area of cross - section is 10290 sq m , the depth of cannel is ?
1 / 2 * d ( 6 + 4 ) = 10290 d = 258 answer : a
divide(divide(divide(10290, divide(add(6, 4), const_2)), const_4), const_2)