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2004 AMC 10A Problem 21

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2004 AMC 10A Problem 21AMC 10 Step by Step
Name:                             Date: September 13, 2026
Circles · difficulty 4 of 5 · about 5 min · position P21-25

Two distinct lines pass through the center of three concentric circles of radii 3, 2, and 1. The area of the shaded region in the diagram is 813\frac{8}{13} of the area of the unshaded region. What is the radian measure of the acute angle formed by the two lines? (Note: π\pi radian is 180180 degree.)
figure

  1. A)

    π8\frac{\pi}{8}

  2. B)

    π7\frac{\pi}{7}

  3. C)

    π6\frac{\pi}{6}

  4. D)

    π5\frac{\pi}{5}

  5. E)

    π4\frac{\pi}{4}

Working