what u have is a 45-45-90 degree triangle...the 2 legs are equal and the hypotenuse is a leg multiplied by the square root of 2.
so one leg is x and the hypotenuse is sqrt 10...
** if ur given the hypotenuse, u can find the legs by dividing the hypotenuse by the square root of 2
** if ur given a leg, u find the hypotenuse by multiplying the leg by the square root of 2.
so the leg (x) = (sqrt 10) / (sqrt 2) = sqrt 5 (or 2.236...thats rounded)