Sketch a graph of $x^{2} + y^{2} = 100$.

1. Is it a function?

   Hint (a):

   Does each x-value on the graph of the function have only one corresponding y-value?

2. What are its domain and range?

   Answer (b):

   Domain: −10 ≤ x ≤ 10
   Range: −10 ≤ y ≤ 10

3. Draw a central angle that measures $\frac { 2 \pi } { 3 }$ radians. If you remove this wedge of the circle, how much area remains?

   Hint (c):

   See the unit circle graph at right.
   What portion of the circle is shaded?

   More Help (c):

   $\text{Since}\:\frac{2\pi}{3}\:\text{is} \ \frac{1}{3}\:\text{of the total angle in a circle, the remaining}$

   $\text{area will be }\frac{2}{3}\:\text{of the total area.}$