Table of Contents

- 1 How do you derive the equation of a circle?
- 2 What does r represent in the equation of a circle?
- 3 What does r represent what happens when r changes?
- 4 What does the r in the standard equation stand for?
- 5 How do you know if an equation represents a point?
- 6 Why is x^2+y^2 the definition of a circle?
- 7 Why is x^2 + y^2 equal to R^2?

## How do you derive the equation of a circle?

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 does r represent in the equation of a circle?

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 R 2?**

The center-radius form of the circle equation is in the format (x – h)2 + (y – k)2 = r2, with the center being at the point (h, k) and the radius being “r”. This form of the equation is helpful, since you can easily find the center and the radius.

**How do you determine whether an equation represents a point a circle or a circle that doesn’t exist?**

If g2+f2−c=0, then it’s a point circle. If g2+f2−c>0, then it’s a real circle. If g2+f2−c<0, then it’s an unreal or imaginary circle.

### What does r represent what happens when r changes?

Simply put, R is the correlation between the predicted values and the observed values of Y. R square is the square of this coefficient and indicates the percentage of variation explained by your regression line out of the total variation. This value tends to increase as you include additional predictors in the model.

### What does the r in the standard equation stand for?

r is the radius of the circle. r is the x coordinate of the center of the circle. r is the y coordinate of the center of the circle. What is the center and the radius of the circle with equation, (x-4)2 + (y-2)2 = 25. Center is (5,2) and radius is 4.

**How do you find the radius of a circle using the general equation?**

The general form of the equation of circle is: x2 + y2 + 2gx + 2fy + c = 0. This general form of the equation of circle has a center of (-g, -f), and the radius of the circle is r = √g2+f2−c g 2 + f 2 − c .

**What is half of a radius called?**

In mathematics (and more specifically geometry), a semicircle is a one-dimensional locus of points that forms half of a circle. The full arc of a semicircle always measures 180° (equivalently, π radians, or a half-turn). It has only one line of symmetry (reflection symmetry).

#### How do you know if an equation represents a point?

Correct answer: To find out if a point (x, y) is on the graph of a line, we plug in the values and see if we get a true statement, such as 10 = 10. If we get something different, like 6 = 4, we know that the point is not on the line because it does not satisfy the equation.

#### Why is x^2+y^2 the definition of a circle?

Because x^2+y^2 represents the square of distance of the moving point p (x,y) from the origin that is (0,0) which is always r^2 ;a constant.that is the difinition of a circle. (locus of a point such that it’s distance from a fixed point is always constant)

**What is the equation of circle with (H) K and (r) radius?**

A circle is a closed curve that is drawn from the fixed point called the centre, in which all the points on the curve are having the same distance from the centre point of the centre. The equation of circle with (h,k) center and r radius is given by: (x-h) 2 + (y-k) 2 = r 2

**What is the equation of a circle with the centre as origin?**

We know that the distance between the point (x, y) and origin (0,0) can be found using the distance formula which is equal to- √ [ x2+ y2 ]= a Therefore, the equation of a circle, with the centre as the origin is, x2+y2= a2

## Why is x^2 + y^2 equal to R^2?

Because the Pythagorean theorem tells you that x^2 + y^2 is the square of the distance from the origin to the point (x, y). Since this is equal to r^2, it means that we are looking at all points which are distance r from the origin.