The point (3,0) lies on a circle with the center at the origin. what is the area of the circle to the nearest hundredth?

Radius = 3 units
Using pi as 3.132
Area of circle =  = 3.142 x 3 x 3 = 28.278 square units ≈ 28.28 square units

OR if you use the calculator and press pi x 3 x 3 = 28.27square units 

Aand b are correctly balanced reactions. they have the same number of atoms in both sides of the reaction