The correct answer is 2 1/6.
Good Luck...:)
The answer to the question should be option B
The diagonal is the hypotenuse of a right triangle with the sides of the square as legs.
By Pythagoras (s = side)
s^2 + s^2 = 15^2
2s^2 = 225
s^2 = 112.5
s = sqrt(112.5)
s = 10.6 cm (to the nearest tenth)
Check the picture below.
let's recall that a rhombu's sides are all equal.