Geometry and TrigonometryEasy–MediumRadius from an equation with a non-square constant
Geometry and Trigonometry practice question
Which of the following is the radius of the circle in the xy-plane whose equation is x² + y² = 50?
- A. 5√2Correct
- B. 50
- C. 25
- D. 10
Answer: A. 5√2
For x² + y² = r², the radius is √50 = √(25 · 2) = 5√2.
Why the other answers are wrong
- B. 50
- 50 is r², not r. Take the square root.
- C. 25
- 25 is half of 50, not its square root.
- D. 10
- 10 would give r² = 100, not 50.
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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