Homework for 4/9/12

In chapter 10, I have learned many things about circles so far. I have learned many terms describing circles such as chord, radius, and diameter, and how to find the area and circumference, or perimeter, of a circle. I found that there are different angles in circles as well including central angles and inscribed angles along with the methods to find them even by using arc measures which I have learned to find. Also, I learned how inscribed polygons can lie in a circle and rules for finding different inscribed angles and quadrilaterals. Futhermore, I have learned what a tangent is and how I can find the measurements of tangent lines. Some careers that involve circles include architects when building structures and ground maintenance workers such as when developing a putting green on a golf course. Another question I still have is that if you extend chords in a circle, wouldn't everything be a secant line or angle then? I also didn't understand our book work for #30.