Geometry and TrigonometryEasy–MediumRadius from a circle's equation
Geometry and Trigonometry practice question
In the xy-plane, a circle has the equation (x + 2)² + (y − 7)² = 25. What is the radius of the circle?
Answer: 5
The right side is r², so r = 5.
Common wrong answers
- If you answered 7
- 7 is the centre's y-coordinate.
- If you answered 25
- 25 is r².
- If you answered -2
- −2 is the centre's x-coordinate.
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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