What is the equation of a circle centered at origin with radius r?
A
x² + y² = r
B
x² - y² = r²
C
x² + y² = r²
D
x + y = r²
Correct Answer: Option C — x² + y² = r²
Explanation:
Standard equation of circle at origin: x²+y² = r². For center (h k): (x-h)²+(y-k)² = r². Circle equations including finding center and radiu...
Standard equation of circle at origin: x²+y² = r². For center (h k): (x-h)²+(y-k)² = r². Circle equations including finding center and radius from general form and tangent line conditions are standard coordinate geometry topics in higher competitive exam papers including CSS and PMS.