Answer:
192cm²
Explanation:
The diagonal of the rectangle is expressed using the formula:
d = √l²+w²
l is the length
w is the width
Given d = 20
20 = √l²+w²
400 = l²+w² .... 1
Since the difference between the length and the width is 4cm, then;
l - w = 4 ... 2
l = 4 + w
Substitute equation 2 into 1;
400 = (4+w)²+w²
400 = 16 +8w + w² +w²
400 = 16 + 8w + 2w²
2w²+8w - 384 = 0
w²+4w - 192 = 0
w = -4±√4²-4(-192)/2
w = -4±√16+768/2
w = -4±28/2
w = -4+28/2
w = 24/2
w = 12
Since l = w+4
l = 12+4
l = 16
Area of the rectangle = 16 * 12
Area of the rectangle = 192cm²