Answer:
The formula for the area of a circle is 3.14*radius². The circumference is 3.14*twice the radius. If you have the diameter, but not the radius, divide the diameter by half and you get the radius. If you are still unclear, tell me what you are unclear about and I can help. If you provide me with a radius or diameter, I can give you the area or circumference with a step by step explanation. If you want me to find the radius or diameter from the area or circumference, I can give you a step by step explanation for it too. I hope this helps!