a)
[tex] {a}^{2} + (2 \sqrt{3} {)}^{2} = (3 \sqrt{3} {)}^{2} \\ {a}^{2} + 4 \times 3 = 9 \times 3 \\ {a}^{2} + 12 = 27 \\ {a}^{2} = 15 \\ a = \sqrt{15} [/tex]
b)
[tex] {3}^{2} + {4}^{2} = {b}^{2} \\ 9 + 16 = {b}^{2} \\ {b}^{2} = 25 \\ b = \sqrt{25} \\ b = 5[/tex]
