Answer:
OB = 5 units
Step-by-step explanation:
OPtion I is right
Given in the picture is a circle.
AB is a chord, O is the centre of the circle
OR is drawn perpendicular to AB.
Given that OR =3, and RB =4
Since ORB is a right triangle with known legs we can find the hypotenuse OB using Pythagorean theorem
[tex]OB^2=OR^2+RB^2=3^2+4^2 =25\\OB =5[/tex]
Hence radius of the circle = 5 units.
