posted by y912f on .
these two are the same type of questions but i have no clue how to figure out the answer. i have tried drawing it out but don't know what to do after that.
1. a bicycle with a 28-inch wheel(diameter) travels a distance of 800 feet. how many revolutions does the wheel make (to the nearest revolution)?
2. A wheel with a 20-inch radius is marked at two points on the rim. the distance between the marks along the wheel is found to be 3 inches. what is the angle (to the nearest tenth of a degree) between the radii to the two marks?
it would be realy helpful if you could explain to me how to figure out these two. thks
1. How far does the wheel go in 1 rotation?
C = piD = pi(28)inches
but 800 feet = 9600 inches
so no of rotations = 9600/(28pi) = 109 to the nearest whole number
for 2. is the 3 inches the straight line distance betweeen the points or is it measured along the arc?
If straight, use the Cosine Law,
If arc length, set up a ratio..
angle/360 = 3/(40pi), solve for "angle"