On the graph, we can see that when x=1, y=0.
But we don't even need to bother opening the attachment
and studying the graph !
In your question, you said that one point on the function is (1, 0) .
That means that when 'x' is 1, 'y' is zero. And there you are !
You have to use the Pythagoreas theorem where you do 3 squared + 4 squared=25
Then you square root 25 which is 5 so
c is 5