Answer:
7√5
Step-by-step explanation:
Let the missing length be x.
Using Pythagoras' Theorem
[tex] {x}^{2} = {7}^{2} + {14}^{2} [/tex]
[tex] {x}^{2} = 49 + 196 = 245[/tex]
Take the square roots of both sides
[tex] { {x} } = \sqrt{49 \times 5} [/tex]
[tex] x= 7 \sqrt{5} [/tex]
Therefore, the missing length is 7√5
