# Volume expression

• October 22nd 2010, 04:34 PM
qhdus
Volume expression
I have been working on this problem for quite awhile now and I can't seem to get the right answer.

A water trough is $8$ m long and its cross-section is an isosceles trapezoid which is $180$ cm wide at the bottom and $240$ cm wide at the top, and the height is $60$ cm. The trough is not full. Give an expression for V, the volume of water in the trough in cm^3, when the depth of the water is d cm.
• October 22nd 2010, 05:33 PM
skeeter
Quote:

Originally Posted by qhdus
I have been working on this problem for quite awhile now and I can't seem to get the right answer.

A water trough is $8$ m long and its cross-section is an isosceles trapezoid which is $180$ cm wide at the bottom and $240$ cm wide at the top, and the height is $60$ cm. The trough is not full. Give an expression for V, the volume of water in the trough in cm^3, when the depth of the water is d cm.

area of the trapezoid formed by water of depth d ...

$\displaystyle A = 180d + \frac{d^2}{2}$

$V = 8A$