Geometry and TrigonometryEasy–MediumArea of a semicircle
Geometry and Trigonometry practice question
A semicircle has a radius of 4. What is its area?
- A. 8πCorrect
- B. 16π
- C. 4π
- D. 2π
Answer: A. 8π
A full circle of radius 4 has area π(4²) = 16π. A semicircle is half: 8π.
Why the other answers are wrong
- B. 16π
- 16π is the area of the FULL circle.
- C. 4π
- 4π halves the radius squared incorrectly (or is π × 4); half of 16π is 8π.
- D. 2π
- 2π is a quarter of the circle's area, or half its... no: half of 16π is 8π.
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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