Try this solution, pls, modify it according to Your requirements:
<u>a=4; b=3; c=2.</u>
additional:
note, (√2-1) is the correct result instead of (1-√2). Short explanation: the result (√2-1) is positive value under the 'square root' sign, the negative values under the 'square root' sign are like restricted operation, finally only (√2-1) result is legal.