For question one, you would need to use the formula pi r ^2. So first you have 4.5, which is your radius(stands for r). Then you square it, which is 20.25. Then, you multiply 20.25 with pi. Then for circumference, you do 2 x pi x the radius which is 4.5. So for area, you get 63.62. Then for circumference you get 28.27. For question 2, it is basically the same steps but instead you a diameter, not a radius. To get the radius, divide by 2, which the radius will be 6. Then from there, the radius is 6, and you solve the question.
ok radius is distance from center to the circle diameter is from one isde to the other, it is also twice the radius r=radius d=diameter circumfernce=pi times diameter or 2 times pi times radius area=pi times radius^2 so 1. circumference=2pir radius=4.5 c=2pir c=2pi4.5 c=9pi in area=pir^2 arae=pi(4.5)^2 area=pi20.25 area=20.25pi in² 2. diameter=12mi circumfernce=pid circumfernce=pi12 circumfnerce=12pi mi area=pir^2 d/2=r 12/2=r=6 area=pi6^2 area=36pi mi²