To find the missing length of this triangle you need to use the Pythagorean Theorem.
As shown in the image we are given three sides: 1, 8 and c and so you have to substitute these numbers into the equation a squared + b squared = c squared.
So it should look like:
1 squared + 8 squared = c squared, so solve it to be
1 + 64 = c squared which is 65 = c squared
Now you have to isolate the variable c because that is what you are trying to find so you must square root both sides:
[tex]\sqrt{65}[/tex] = c
So that should be your answer.
Hope this helps!
(if it doesn't work then you might have to simplify)
