Circles

Khan Academy:

1.   Pythagorean Theorem and Radii of Circles (5:52)Finds missing segments of triangles within a circle using the Pythagorean Theorem.
2.   Features of a circle from its equation in standard form (3:50)
   Finding the center and radius of a circle from the equation in standard form.  Given $(x+3)^2 + (y-4)^2 = 49$, find the center and radius. Solution: center is $(-3,4)$ and radius is $7$.
3.   Features of a circle from its equation in standard form.
   Find the center and radius of .
4.   Features of a circle from its expanded equation (4:20)Graph the circle (Puts the equation into standard form by completing the square.)
5. Features of a circle from its expanded equation.Find the center and radius of the circle

PatrickJMT:

1. Finding the Center-Radius Form of a Circle by Completing the Square – Example 1
2. Finding the Center-Radius Form of a Circle by Completing the Square – Example 2
3. Finding the Center-Radius Form of a Circle by Completing the Square – Example 3