One side of a rectangle is 3 cm shorter than the other side. If we increase the length of each side by 1 cm, then the area of the rectangle will increase by 20 cm2. Find the lengths of all sides.
Choose one
A) 10 and 3	B) 7 and 10	C) 11 and 8	D) 3 and 10	E) 10 and 10
Let x be the length of the longer side x&gt;3, then the other side's length is x−3 cm. Then the area is S1 = x(x - 3) cm2. After we increase the lengths of the sides they will become (x+1) and (x−3+1)=(x−2) cm long. Hence the area of the new rectangle will be A2=(x+1)⋅(x−2) cm2, which is 20 cm2 more than the first area. Therefore   A1+20=A2   x(x−3)+20=(x+1)(x−2)   x2−3x+20=x2+x−2x−2   2x=22   x=11. So, the sides of the rectangle are 11 cm and (11−3)=8 cm long.   So answer is 11 and 8.
<result>C</result>
One side of a rectangle is 3 cm shorter than the other side. If we increase the length of each side by 1 cm, then the area of the rectangle will increase by 20 cm2. Find the lengths of all sides.