A rectangles base is 9cm longer than its height. The rectangle's area is 90cm squared. Find this rectangle's dimensions.

Assume that the length of the rectangle is l and the width is w.

From the givens, we can conclude that:

l=9+w

Area of rectangle=l * w

90 = (l * w) = (9+w) (w)

90=9w+w^2

w^2+9w-90 = 0

either w=6

or w=-15 (this value is rejected as length cannot be negative)

therefore, the dimentions are as follows:

length=9+6=15 cm

width=6 cm