The lengths of the sides of a right angled triangle are (3x + 1)cm, (3x – 1)cm and xcm. Find x
-
A.
2 -
B.
6 -
C.
18 -
D.
12 -
E.
5
Correct Answer: Option D
Explanation
((3x + 1)^{2} = (3x – 1)^{2} + x^{2}) (Pythagoras’s theorem)
(9x^{2} + 6x + 1 = 9x^{2} – 6x + 1 + x^{2})
x2 – 12x = 0
x(x – 12) = 0
x = 0 or 12
The sides cannot be 0 hence x = 12.