Coterminal angles are angles that are the same but written differently. Circles have 360 degrees, so an angle that goes above this threshold has completed one revolution. For example, a 450 degree angle would be in the same position as a 90 degree angle. 

To find a positive coterminal angle, add 360 degrees to the initial value. 

To find the negative coterminal angle, simply subtract 360. The only exception to this rule would be if the initial value were greater than 360. In this case, subtract 360 until the value is negative, making it a negative coterminal. Therefore, 

160-360 = -200

Do this a second time and we get -560. These are examples of negative coterminal angles. 

The circle is represented by the formula:

Although some of the equations might not in this form, we can see by the variables that the equation   is most similar to the form.

Multiply two on both sides of the equation and we will have: 

This is an equation of a circle.  The other equations represent other conic shapes.

The answer is:  

Definition of the formula of a circle:

Where:

is the coordinate of the center of the circle

is the  coordinate of the center of the circle

is the radius of the circle

Plugging in values:

In order to solve for the radius, we will need to complete the square twice.  

Group the x and y-variables in parentheses.  Starting from the original equation:

Add two on both sides. 

Divide by the second term coefficient of each binomial by 2, and add the squared quantity on both sides of the equation.

The equation becomes:

Factorize both polynomials in parentheses and simplify the right side.

The center is: 

The radius is:  

The answer is:  

The equation of a circle in standard for is:

Where the center  and the radius of the cirlce is .

Dividing by 4 on both sides of the equation yields

or

an equation whose graph is a circle, centered at (2,3) with radius = .5

Look at the formula for the equation of a circle below. 

Here  is the center and  is the radius. Notice that the subtraction in the center is part of the formula. Thus, looking at our equation it is clear that the center is  and the radius squared is . When we square root this value we get that the radius must be . 

The equation for a circle with center  and radius  is :

Our circle is centered at  with radius , so the equation for this circle is :

The parent equation of a circle is represented by . The radius of the circle is equal to . The radius of the cirle is .

The equation can be rewritten so that it looks like the parent equation for a circle . After completeing the square, the equation changes from  to . From there it can be expressed as . Therefore the center of the circle is at .

Rewrite the equation of the circle in standard form

as follows:

Since  and , we complete the squares by adding:

The standard form of the equation sets 

,

so the radius of the circle is