Geometry and TrigonometryEasy–MediumArea from a diameter
Geometry and Trigonometry practice question
What is the area of a circle with diameter 10?
- A. 25πCorrect
- B. 100π
- C. 10π
- D. 5π
Answer: A. 25π
The radius is half the diameter, 5. Area is πr² = π(5)² = 25π.
Why the other answers are wrong
- B. 100π
- 100π uses the diameter in place of the radius: π(10)². Halve the diameter first.
- C. 10π
- 10π is the circumference, π × diameter. Area uses πr².
- D. 5π
- 5π is π times the radius. The radius must be squared: 5² = 25.
More Geometry and Trigonometry questions
- Easy–Medium
A circle has a radius of 6. What is its area? (Use A = πr².) - Easy–Medium
A right triangle has legs of length 6 and 8. What is the length of the hypotenuse? - Easy–Medium
A circle has a radius of 5. What is its circumference? (Use C = 2πr.) - Easy–Medium
What is the midpoint of the segment joining the points (2, 3) and (8, 11)? - Easy–Medium
What is the measure, in degrees, of angle B? - Easy–Medium
What is the area, in square centimeters, of the trapezoid?
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