Given the value of b and c, we want to get the value of a
The three sides represent the sides of a right triangle
By the use of Pythagoras' theorem, we can get the value of a
From the diagram, the disgonal represents the hypotenuse of the right triangle
According to Pythagoras' theorem, the square of the hypotenuse equals the sum of the squares of the two other sides
Thus, we have it that;
[tex]\begin{gathered} c^2=a^2+b^2 \\ 6^2=3^2+a^2 \\ 36=9+a^2 \\ a^2\text{ =36-9} \\ a^2\text{ = 27} \\ \text{a = }\sqrt[]{27} \\ a\text{ = 5.2 units} \end{gathered}[/tex]