Here you want to use the Pythagorean Theorem.
\(a^{2} + b^{2} = c^{2}\)
Remember that the hypotenuse ( c ) will always be the longest side, opposite of our right angle.
let's enter in the numbers on the picture into our theorem.
\(4^{2} + 1^{2} = c^{2}\)
now lets simplify
\(4^{2} = 16 \\ 1^{2} = 1 \\ \\ 16 + 1 = c^2 \\ \\ 17 = c^2 \\ \\ \sqrt{17} =c\)
and there you are! \(\sqrt{17} = c\)
Hope this helped!:)
