Hello!
You first have to find the width
We can find this use the Pythagorean theorem
12^2 + b^2 = 15^2
Square the numbers
144 + b^2 = 225
Subtract 144 from both sides
b^2 = 81
Take the square root of both sides
b = 9
The width is 9
To find the perimeter you do 2l + 2w
Put in the values 2(12) + 2(9)
24 + 18 = 42
The perimeter is 42cm
To find the area you multiply the sides
12 * 9 = 108
The area is 108cm^2
The answer is D
Hope this helps!
