P is just a definition: it's the ratio between a circle's diameter and its circumference. In other words, any circle circumference is approximately 3.14 (p) times longer (around) than its diameter length. Some old Greek dude discovered it a few thousand years ago... Let's do the first 3 problems together - by then I think you'll have confidence you can do the remaining 3! 1. If C = 2pr, then we substitute C = 2*3.14*6, = 37.68 2. If C = 2pr, then let's rearrange that so we can find r: divide both sides (to keep it equal) by 2p to get r by itself: C/2p = 2pr/2p, so r = C/2p. Now substitute: r = 24p/2p = 12 3. If C = 2pr, then r = C/2p (see #2 above), then r = d/2. If A = pr2, then A = p (C/2p)2. Substitute: A = p (32p/2p)2, or A = p (16)2 A = 3.14 * 256 = 803.84 Now can you complete #3 - #6? I bet you can... :-)
