# SAT Math Multiple Choice Question 980: Answer and Explanation

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**Question: 980**

**16.**

In the figure above, circle *O* has a circumference of 12π. If *AB* = 8, what is *BC*

- A.
- B.
- C.
- D.

**Correct Answer:** B

**Explanation:**

**B**

**Difficulty:** Hard

**Category:** Additional Topics in Math / Geometry

**Strategic Advice:** Identify pieces of the figure that play roles in multiple shapes present (for example, a radius of the circle that is also a leg of a triangle), and transfer information as you work toward the answer.

**Getting to the Answer:** The circumference of circle *O* is 12π, so its radius must be 6(*C* = 2π*r*). You now know the lengths of two sides of Δ*AOB* (the given hypotenuse and the leg represented by the radius), and because it's a right triangle, you can use the Pythagorean theorem to find the length of the missing side (*OB*):

Don't stop yet; the question asks for *BC*, not *OB*. *BC* is equal to 6 - 2 , which is (because is also a radius). Factor out a 2 to get, which matches (B).