Presentation on theme: "Graphing and Writing Equations"— Presentation transcript:
1Graphing and Writing Equations CirclesGraphing and Writing Equations
2What is a circle? A conic formed when…. A second degree equation… A locus of points…
3Definition as a conicA circle is a conic or a conic section because it is formed by the intersection of a plane and a double-napped cone.
4Algebraic Definition A circle is defined as the second degree equation Ax2+Bxy+Cy2 +Dx+Ey+F = 0when A = C.
5A circle is a locus of points….. But, what is a locus…?A locus is the set of all points, and only those points, that satisfy one or more conditions.So, “ A locus of points in a plane 10 cm from a point A” gives a geometric description of a circle with center A and a radius of 10
6Geometric DefinitionA circle is the locus or collection of all points (x, y) that are equidistant from a fixed point, (h, k) called the center of the circle.The distance r , between the center and any point on the circle is the radius
7Using the distance formula, you can derive the standard form of a circle.(x- h)2 + (y- k)2 = r 2where, center = (h, k) and radius = r
8Equation of a circle:Practice Problems to write the equation of a circle when given the center and the radius.
9What if the center and radius are not given? Try these :Center = (0,3) and solution point = (0, 6)Endpoints of diameter are (-2,3) and (6,5)Center on the line y = 2, and tangent to the x-axis at (3,0)
10Graph the circleTo graph a circle, locate all the points that are a fixed distance r, from the center (h, k).Click here to graph a circle
11Graph a circle with center at the origin Example: Graph x2 + y2 = 4
12To Graph a Circle center (h,k) and radius r Example: (x-3)2+ (y-3)2 =4Click Here To graph a circle if given a radius and a center
13What are some applications? Circular orbits of the earth for satellites.Perfect shape for cross-section of a submarine.GearsOther