Which statement about the diameter and radius is true?

Which statement about the diameter and radius is true?

• A. The diameter is equal to the radius
• B. The diameter is half the radius
• C. The diameter is equal to the circumference
• D. The diameter is twice the radius

Answer: (D)

In a circle, the radius is the distance from the center to any point on the circle, while the diameter runs from one edge of the circle to the opposite edge through the center. This means the diameter spans across two radii, so its length is twice the radius. If the radius is r, the diameter is 2r. For a quick check, if the radius is 5 units, the diameter is 10 units. The diameter cannot be equal to the radius (that would force r = 2r, impossible for a nonzero circle), nor can it be half the radius or equal to the circumference, since the circumference is the curved distance around the circle, not a straight line. Hence the diameter is twice the radius.

In a circle, the radius is the distance from the center to any point on the circle, while the diameter runs from one edge of the circle to the opposite edge through the center. This means the diameter spans across two radii, so its length is twice the radius. If the radius is r, the diameter is 2r. For a quick check, if the radius is 5 units, the diameter is 10 units. The diameter cannot be equal to the radius (that would force r = 2r, impossible for a nonzero circle), nor can it be half the radius or equal to the circumference, since the circumference is the curved distance around the circle, not a straight line. Hence the diameter is twice the radius.