Charlie's Blog

In sections 7-1 through 7-6 that we have learned so far, I understood most of them. Some things took a little further explanation though. One thing I understood very well was the Sector's of a Circle (I just wasn't very good at remembering the formulas). The concept of this is to use one or more of the three formulas that we are given: k=1/2r^2theta, s=rtheta, and k=1/2rs. The problem tells you whether you have to solve to find the arc length (s), the radius (r), the central angle (theta), or the area (k). Some problems have you solve for one of these by giving you the other measurements, other problems have you solve for two.

**Some helpful hints for word problems: - diameter is another word for the arc length (s) - the apparent size is another name for the central angle (theta) - distance between the two objects is another name for the radius (r)

For Example:
The orange's apparent size is 3/7 rads. with an diameter of 7 cm. Find the distance between the orange and the bowl of fruit that's on the table.
theta= 3/7 rads.
s= 7 cm
r= ?
7 = r(3/7)
Divide 7 by 3/7 and you get that r = 16.3333
So the distance between the bowl and the orange is 16.3333 cm

In this problem it gave you the diameter (arc length), the apparent size (central angle), and asked you to solve for the distance (radius). By dividing the apparent size by the diameter, you got the distance between the two objects.