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Circles — SAT practice questions

Practice 136 Circles questions in the app

What this topic is

Circles on the SAT Math test covers circumference, radius, central angles, arc length, chords, and angles in standard position given in radians.

A student has to find arc length from a circumference such as 36π and a central angle of 120°, find chord length when the radius is 6, and work from an angle measuring (3π)/4. Questions are multiple choice with four answer choices or student-produced response and often include a diagram.

Common traps are mixing degrees and radians, using radius in place of diameter, and confusing arc length with sector area, so the choices usually include those nearby wrong values.

Sample questions

Pick an answer to see whether it is right — nothing is saved, and nothing needs an account.

Question 1Easier

In a circle with center CC, points AA and BB lie on the circle and ACB=90\angle ACB=90^\circ. The radius of the circle is 6. What is the length of chord AB\overline{AB}?

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Answer: B — 626\sqrt{2}

ACB\triangle ACB is an isosceles right triangle with legs 6, so AB=62AB=6\sqrt{2}.

Question 2Easier

A circle has circumference 36π36\pi. An arc of the circle has a central angle of 120120^\circ. What is the length of the arc?

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Answer: C — 12π12\pi

12036036π=12π\dfrac{120}{360}\cdot36\pi=12\pi.

Question 3Easier

An angle in standard position has measure 3π4\dfrac{3\pi}{4}. What is the value of sin3π4\sin \dfrac{3\pi}{4}?

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Answer: A — 22\dfrac{\sqrt{2}}{2}

The angle 3π4\dfrac{3\pi}{4} is in Quadrant II, where sine is positive. Its reference angle is π4\dfrac{\pi}{4}, so sin3π4=22\sin \dfrac{3\pi}{4}=\dfrac{\sqrt{2}}{2}.

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Practice 136 Circles questions in the app

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