Geometry

Question Analysis

The main focus is to use the standard form of the circle equation to find the equation of a circle given its radius and center at the origin.

 

Key Concept Explanation

The standard form of a circle's equation is , where  is the center of the circle and  is the radius. When the center is at the origin , the equation simplifies to .

 

Step - by - Step Solution

1. Identify the values of , , and :

Since the center is at the origin,  and . The radius .

2. Substitute the values into the standard form:

Substituting into , we get .

Simplifying, we have .

 

Option Analysis

A.

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