The perimeter of a rhombus is 120 feet and one of its diagonal has a length of 40 feet. Find the area of the rhombus.
Choose the correct choice from the following:
A) 100 sqrt(5) ft.sq	B) 400 sqrt(5) ft.sq	C) 500 sqrt(5) ft.sq	D) 200 sqrt(5) ft.sq	E) 150 sqrt(5) ft.sq
A perimeter of 120 when divided by 4 gives the side of the rhombus 30 feet. The length of the side OC of the right triangle is equal to half the diagonal: 20 feet. Let us now consider the right triangle BOC and apply Pythagora's theorem to find the length of side BO.   30^2 = BO^2 + 20^2   BO = 10 sqrt(5) feet   We now calculate the area of the right triangle BOC and multiply it by 4 to obtain the area of the rhombus.   area = 4 ( 1/2) 400 sqrt(5) ft.sqO * OC = 4 (1/2)10 sqrt (5) * 20   = 400 sqrt(5) ft.sq   Answer is 400 sqrt(5) ft.sq
<result>B</result>
The perimeter of a rhombus is 120 feet and one of its diagonal has a length of 40 feet. Find the area of the rhombus.