**How to find the equation of a circle?**

- Choose the center O = (A, B) of your circle. Don’t choose it as the origin of the coordinate system.
- Draw a circle with a chosen radius r .
- Pick any point on the circle. Assume the coordinates of that point are P = (x,y) .
- The angle POC is equal to α.

**How to find the equation of a circle?**

- Choose the center O = (A, B) of your circle. Don’t choose it as the origin of the coordinate system.
- Draw a circle with a chosen radius r .
- Pick any point on the circle. Assume the coordinates of that point are P = (x,y) .
- The angle POC is equal to α.

**How to Find the Equation of a Circle**

- Write the Standard Form of the equation for a circle centered at point (-2 , -8) and has a radius of 4. (x + 2)^2 + (y + 8)^2 = 16. (x – 2)^2 + (y – 8)^2 = 16.
- Convert the following Standard Form equation to an equation in General Form: (x – 7)^2 + (y + 3)^2 = 49.

We know that the general equation for a circle is ( x – h )^2 + ( y – k )^2 = r^2, where ( h, k ) is the center and r is the radius.

## How do you find the equation of a circle given two points?

Use the Distance Formula to find the equation of the circle. Substitute (x1,y1)=(h,k),(x2,y2)=(x,y) and d=r . Square each side. The equation of a circle with center (h,k) and radius r units is (x−h)2+(y−k)2=r2 .

## What are all the formulas for a circle?

We use the circle formula to calculate the area, diameter, and circumference of a circle. The length between any point on the circle and its center is known as its radius.

Formulas Related to Circles.

Diameter of a Circle | D = 2 × r |
---|---|

Circumference of a Circle | C = 2 × π × r |

Area of a Circle | A = π × r2 |

## How do you find the equation of a circle with endpoints?

Given the endpoints of the diameter of a circle, find its equation

## What is the equation for a semicircle?

In the case of a circle, the formula for area, A, is A = pi * r^2, where r is the circle’s radius. Since we know that a semicircle is half of a circle, we can simply divide that equation by two to calculate the area of a semicircle. So, the formula for the area of a semicircle is A = pi * r^2/2.

## What is the arc length formula?

Calculate the arc length according to the formula above: L = r * Θ = 15 * π/4 = 11.78 cm . Calculate the area of a sector: A = r² * Θ / 2 = 15² * π/4 / 2 = 88.36 cm² . You can also use the arc length calculator to find the central angle or the radius of the circle.

## What is 2π?

A full circle has 2π radians (Roughly 6.28) As seen in the figure above, a radian is defined by an arc of a circle. The length of the arc is equal to the radius of the circle.

## What is called circle?

Circle is the locus of points equidistant from a given point, the center of the circle. A circle is a plane figure contained by one line, which is called circumference, and is such, that all straight lines drawn from a certain point within the figure to the circumference, are equal to one another.

## Are formula for circle?

from a central point. from the center. Circle: The set of all points on a plane that are a fixed distance from a center.

Circle on a Graph.

x | y | x2 + y2 |
---|---|---|

5 | 02 + 52 = 0 + 25 = 25 | |

−4 | −3 | (−4)2 + (−3)2 = 16 + 9 = 25 |

−5 | 02 + (−5)2 = 0 + 25 = 25 |

2 more rows

## What are the endpoints of a circle?

The distance from a circle’s center to a point on the circle is called the radius of the circle. A radius is a line segment with one endpoint at the center of the circle and the other endpoint on the circle.

## What is general equation of a circle?

The General Form of the equation of a circle is x2 + y2 + 2gx +2fy + c = 0. The centre of the circle is (-g, -f) and the radius is √(g2 + f2 – c). Completing the square. Given a circle in the general form you can complete the square to change it into the standard form.

## What is area of a circle?

Area of a circle. The area of a circle is pi times the radius squared (A = π r²). Learn how to use this formula to find the area of a circle when given the diameter.