the picture at the right shows the garden in roberts yard.it's a triangle with a right angle,and it's lenght is 9ft,width is 15ft,and height is 12 ft,he wants 2 cover the garden with plastic bc of a sudden drop in temperature.how many square yards of plastic does he need?

To find this area, you should have the length of the base and the length of the height. Your problem isn't clear about which of the measurements is the base.

like how i did it,i got 15ft multiply it with 12 ft wit 9 ft and got 1620 den i divide it by 3 and got 540.so is 540 the answer

Assuming the base is 9 feet, then use this formula:

A = 1/2 * b * h

A = 1/2 * 9 * 12
A = 1/2 * 108
A = 54 square feet

so 1620 is the answer

Ms. sue were did u get

1/2 from?

Study this site carefully.

http://www.mathgoodies.com/lessons/vol1/area_triangle.html

thx