Answer: 5 units
Step-by-step explanation:
The standard form of equation of circle:
[tex](x-h)^2+(y-k)^2=r^2[/tex] , where (h,k) = center of circle, r= radius.
Given : Center of circle= origin = (0,0) =(h,k)
Point on circle = (3,4)
Put x= 3 , y=4 , h=0 , k=0 , then the equation will become
[tex](3-0)^2+(4-0)^2=r^2\\\\\Rightarrow\ 9+16=r^2\\\\\Rightarrow\ 25=r^2\\\\\Rightarrow\ r=5[/tex]
Hence, the radius is 5 units long.