Math Help - Volume help

1. Volume help

A water trough is 8 m long and its cross-section is an isosceles triangle which is 50 cm wide at the top, and the height is 50 cm. The trough is not full. Give an expression for V, the volume of water in the trough in cm3, when the depth of the water is d cm.

Ive, tried it all. but come up short...i got 100000 in my answer but thats not in terms of d. HELP PLZ?!?!

2. height of the water is d

water is d units wide across the top (similar triangles are proportional)

V = (triangular base area)(length of trough)

$V = \frac{1}{2} \cdot d^2 \cdot 8$

$V = 4d^2$

3. thanks, but it was 800 not 8 because 8 is in m. thanks again though