SAT Practice Questions: Circle Arcs and Sectors

By Ron Woldoff

The SAT Math exam may ask you to deal with, not a whole circle, but only part of it. For example, you may be asked to find the length of an arc (which is part of the circumference of a circle) or the area of a sector (which is part of the area of a circle).

The following practice questions ask you to find the area of a sector as a fraction of the circle, and the circumference of a circle based on the length of an arc.

Practice questions

In the following figure, point O is the center of the circle.

sat1001_arcs

  1. What fraction of the circle is minor arc AOB?
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  2. If the length of minor arc AOB is
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    what is the circumference of the circle?
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Answers and explanations

  1. The correct answer is Choice (C).
    The entire circle is 360 degrees. Place the 30-degree angle over 360 degrees and reduce it to 1/12.
  2. The correct answer is Choice (D).
    If minor arc AOB is 1/12 of the circle
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    then 1/12 of the circle is
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