review of circles

Conic are graphs in shapes. There are 4 common conics such as ellipses, porabolas, hyperbolas and circles which we are doing.

*Standard form of a circle is (x-h)^2+(y-k)^2=r^2 wear (h,k) is the center4 and r is the radius.

*You can find the radius using the distance formula with the center and a point on the out or you can half the diameter foudn by usuing two points on the outside through the center.

*Equations must be put in standard form by the completing the sqaure when found all points:
1.Divide by leading coefficient, move all numbers to the right
2.Half the middle term, then square it and add to both sides
3.factor

*To graph in you calculator y9ou must solve for y and put a + # formulas in Y= slot.

* To find the intersection of a line adn circle
1.Solve the line for y
2.Plug into the circle equation
3.Solve the quadratic
4.If you get a irrational number they do not intersect

EX1.Write an equaton for the circle with a radius of 4 and center points (3,1)
1.Use cirlce formula (x-h)^2+(y-k)^2=r^2. Then plug in
2.(3-h)^2+(1-k)^2=16

*You can be asked to find the radius and center point of an equation. Just work it backwards.