Find the radius of the circle x^2+y^2-2x-2y-47 = 0.
Answer and explanation
Correct answer: B. 7
- Step 1: Complete the square: (x - 1)^2 + (y - 1)^2 = 49.
- Step 2: The radius is the square root of 49, which is 7.
Answer
7.
Why not the others: '49' reports r^2 instead of r; '47' uses the constant term as the radius; '2' uses a^2 + b^2, which is the squared distance from the origin to the centre.
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