Math: Geometry and Trigonometry

SAT Question of the Day for October 30, 2026

A circle has a diameter of 1616 centimeters. What is the circumference of the circle, in centimeters?
  1. A.64π64\pi
  2. B.256π256\pi
  3. C.8π8\pi
  4. D.16π16\piCorrect answer

Explanation

The circumference of a circle is C=πdC = \pi d, where dd is the diameter. With d=16d = 16: C=16πC = 16\pi centimeters. The value 8π8\pi comes from using the radius (r=8r = 8) in the formula πr\pi r instead of 2πr2\pi r or πd\pi d, effectively halving the result. The value 64π64\pi results from using the area formula for the radius, computing πr2=π(8)2=64π\pi r^2 = \pi(8)^2 = 64\pi. The value 256π256\pi comes from using the diameter in the area formula: π(16)2=256π\pi(16)^2 = 256\pi.

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