Math Problem Statement

The equation of a circle is given below. Identify the radius and center. Then graph the circle.

(x+2)^2 + (y-1)^2 = 9

Solution

The given equation of the circle is:

(x+2)2+(y1)2=9(x+2)^2 + (y-1)^2 = 9

This equation is in the standard form of a circle, which is:

(xh)2+(yk)2=r2(x - h)^2 + (y - k)^2 = r^2

where:

  • (h,k)(h, k) is the center of the circle, and
  • rr is the radius.

Step 1: Identify the center and radius

  • From the given equation (x+2)2+(y1)2=9(x + 2)^2 + (y - 1)^2 = 9, we can compare it to the standard form.
    • The center (h,k)(h, k) is (2,1)(-2, 1), because (x+2)(x + 2) can be rewritten as (x(2))(x - (-2)), and (y1)(y - 1) matches the (yk)(y - k) form.
    • The radius rr is the square root of 9, which is r=3r = 3.

Conclusion:

  • Center: (2,1)(-2, 1)
  • Radius: 33

Step 2: Graph the Circle

To graph the circle, plot the center (2,1)(-2, 1) on a coordinate plane. Then, from the center, move 3 units in all directions (up, down, left, right) to mark points on the circle. You can sketch the circle by connecting these points smoothly.

Would you like me to generate a graph of the circle for you?


If you have any further questions or need more details, feel free to ask!

Here are some related questions to explore:

  1. How do you derive the standard form of a circle from the general equation of a circle?
  2. How can you convert from general form to standard form for circles?
  3. What are the differences between an equation of a circle and the equation of other conic sections, like ellipses or hyperbolas?
  4. How do you calculate the area and circumference of a circle from its radius?
  5. What happens if the right-hand side of the equation changes (e.g., =16=16 instead of =9=9)?

Tip: When graphing a circle, make sure to remember that the radius is the distance from the center to any point on the circle.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Circles
Geometry
Coordinate Geometry

Formulas

Standard form of a circle: (x - h)^2 + (y - k)^2 = r^2

Theorems

Equation of a Circle in Standard Form

Suitable Grade Level

Grades 8-10