ACT · Plane Geometry · Circles, arcs, and chords
Question act-q-00487
Medium Multiple choice No calculator
The question
A circle has radius 6. What is its area, in terms of π?
- 6π
- 36π
- 12π
- 72π
Show answer & worked solution
Answer: 36π
Worked solution. Area of a circle is πr². Here r = 6, so area = π × 6² = 36π.
Why each wrong choice is wrong. Confusing area (πr²) with circumference (2πr) is the dominant error here. The 2πr distractor catches it perfectly.
Test-day tactic. Area scales as the square of the radius; circumference scales linearly. When in doubt, sketch a unit circle and check.
About this question type
Items test the basic circle formulas, arc length and sector area as fractions of the whole, inscribed-angle relationships, and the tangent-radius perpendicularity.
You will see a question shaped like this one on roughly every other official ACT form, typically at a moderate position in the section — solidly within the range that separates a 600-band student from a 700-band student. Treat any miss in this subtopic as a signal to drill the subtopic page before you do another full practice test.