triangle question

what is c in the formula c^2 = b^2 +a^2 if a=6 and b=10 ?

$$\small{\text{$ \begin{array}{rcl} c^2 &=& b^2 + a^2 \quad | \quad \mathbf{b = 10} \rm{~~and~~} \mathbf{a = 6} \\ c^2 &=& 10^2 + 6^2 \\ c^2 &=& 100 + 36 \\ c^2 &=& 136 \quad | \quad \pm\sqrt{} \\ c &=& \pm\sqrt{136} \\ c_1 &=& +\sqrt{136} = 11.6619037897\\ c_2 &=& -\sqrt{136} = -11.6619037897\\ \end{array} $}}$$