Geometry and Trigonometry practice question

Answer: A. 64π

C = 2πr = 16π gives r = 8. Then A = πr² = 64π.

Why the other answers are wrong

B. 16π

16π reuses the circumference number as if it were r². The radius is 16π/(2π) = 8, and 8² = 64.

C. 256π

256π squares 16 — the diameter, not the radius. r = 8, so r² = 64.

D. 8π

8π uses the radius without squaring it. Area is πr², so π × 64.

More Geometry and Trigonometry questions

• Medium
  In a 45°-45°-90° right triangle, each leg has length 5. What is the length of the hypotenuse?
• Medium
  A cylinder has a radius of 3 and a height of 10. What is its volume? (Use V = πr²h.)
• Medium
  In a right triangle, the side opposite angle θ has length 3 and the hypotenuse has length 5. What is sin θ?
• Medium
  Two triangles are similar with a ratio of 2 to 3. A side of the smaller triangle measures 8. What is the lengt…
• Medium
  What is the distance between the points (1, 2) and (4, 6) in the coordinate plane?
• Medium
  A circle has a radius of 6. What is the area of a sector with a central angle of 60°?