The length of a rectangular painting is 3 inches longer than its width. If the diagonal is 15 inches long, what is the length of the painting

A^2+b^2 = 15^2

b=a-3

Use substitution

a^2 + (a-3) ^2 = 225

a^2+a^2-6a+9=225

2a^2-6a=-216

2a^2-6a+216=0

2 (a^2-3a+108)

2 (a-12) (a+9)

(a-12) = 0

a=12

(a+9) = 0

a=-9

A is - 9 or 12, but since an object can't have a negative length or width, a must be 12.

Plug this value of a in.

b = (12) - 3

b=9

Final answer: Length=9, width=12

the previous answer is wrong, the length of the painting is 12 inches.