Since the triangle is right angled, we may use pythagoras theorem to find the third side.
Pythagoras theorem :-
KI^2 + JI^2 = KJ^2
substituting the known values in the formula,
x^2 + 3^2 = 5^2
x^2 + 9 = 25
x^2 = 25 - 9
x^2 = 16
x = √16
x = 4
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•°• value of x is 4cm
