Geometry and TrigonometryHardDiameter from a circle's equation
Geometry and Trigonometry practice question
In the xy-plane, a circle has the equation (x − 1)² + (y + 2)² = 49. What is the length of a diameter of the circle?
Answer: 14
r² = 49, so the radius is 7 and the diameter is 14.
Common wrong answers
- If you answered 7
- 7 is the radius.
- If you answered 49
- 49 is r², not a length.
- If you answered 98
- 98 doubles r² instead of r.
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