The answer is the Pythagorean theorem, which states that for a right triangle, the sum of the squares of the two legs (sides a and b) is equal to the square of the length of the hypotenuse (side c). In this case, we have a right triangle with sides a, b, and c, where side b is unknown. We know that 0 is between b and c, so we can write c = b + 0, or c - b = 0. We also know that the values of c and 0 are known, so we can substitute these values into the Pythagorean theorem to get:
a^2 + b^2 = c^2
a^2 + b^2 = (b + 0)^2
a^2 + b^2 = b^2 + 2b(0) + 0^2
a^2 = 2b(0)
b = sqrt(a^2/(2*0))
Thus, if the values of c and 0 are known, the value of side b can be determined using the Pythagorean theorem.