a)
[tex] {4}^{2} + {7}^{2} = {x}^{2} \\ 16 + 49 = {x}^{2} \\ 65 = {x}^{2} \\ x = \sqrt{65} [/tex]
b)
[tex] {4}^{2} + {y}^{2} = (4 \sqrt{10} {)}^{2} \\ 16 + {y}^{2} = 16 \times 10 \\ {y}^{2} = 160 - 16 \\ {y}^{2} = 144 \\ y = \sqrt{144} = 12[/tex]
c)
[tex] {4}^{2} + {z}^{2} = {9}^{2} \\ 16 + {z}^{2} = 81 \\ {z}^{2} = 65 \\ z = \sqrt{65} [/tex]
