A water trough is 8m long and its cross-section is an isosceles triangle which is 60cm wide at the top, and the height is 60cm. The trough is not full.

Question

Give an expression for V, the volume of water in the trough in cm^3, when the depth of the water is d cm.

Thank you in advance!!

Answer 1

draw a diagram. You can see that when the depth is d, the width of the cross-section is also d. So, the area of the cross-section is 1/2 d^2.

v = 1/2 d^2 * 800 cm^3