The height and base of a triangle are in ratio 1:3 respectively. If the area of the triangle is 216 cm(^2), find the length of the base.

A.
24cm 
B.
36cm 
C.
72cm 
D.
144cm
Correct Answer: Option B
Explanation
Area = (frac{1}{2} times base times height)
(height : base = 1 : 3)
(implies base = 3 times height)
Let height = h;
Area = (frac{1}{2} times 3h times h = 216)
(3h^2 = 216 times 2 = 432)
(h^2 = frac{432}{3} = 144)
(h = sqrt{144} = 12.0 cm)
(therefore base = 3 times 12 = 36 cm)