Posted by **Eunice** on Wednesday, April 21, 2010 at 8:23am.

A coin of radius 1 cm is tossed onto a plane surface that has been tesselated by right

triangles whose sides are 8 cm, 15 cm, and 17 cm long. What is the probability that the

coin lands within one of the triangles?

- math/geometry pls help -
**bobpursley**, Wednesday, April 21, 2010 at 9:38am
well, if it is entirely within, it cannot touch any corner or side.

STart with the area along the sides the center of the coin cannot be in.

The center has to be greater than .5cm from any side. Draw the original triangle. Now mark a line parallel to each side, inside the triangle, .5 from the parallel side. These three lines make a triangle inside, in which the center may reside.

label the inner triangle a, b, c, with the a side parallel to 8, b parallel to 15, and c parallel to 17.

a/8=b/15=c/17 similar triangles.

but a= 8-.5-.5-.5(8/15) If you examine the 17 corner carefully, you can arrive at that with using smaller triangles which are similar.

solve for a: a= 6.86

which means b: b= a*15/8=12.86

area of inner triangle= 1/2 ab=44.1

area of original triangle= 1/2 8*15=60

Pr(coin inside)= areainner/areaouter

## Answer This Question

## Related Questions

- Geometry - A coin of radius 1 cm is tossed onto a plane surface that has been ...
- Math - Luis has a coin that is weighted so that the probability that Heads ...
- math - a fair coin is tossed in the air 4 times. if the coin lands heads up the ...
- Math - A biased coin is tossed 3 times. The probability that the coin will land ...
- MATH - 24 1c coins are set out in a row on a table. Then every 2nd coin is ...
- physics - A U.S quarter is rolling on the floor without slipping in such a way ...
- physics - A U.S quarter is rolling on the floor without slipping in such a way ...
- GEOMETRY - if a die is tossed and a coin is flipped, what is the probability of ...
- math - an unbiased coin is tossed 3 times. find the probability that the coin ...
- physics - A U.S quarter is rolling on the floor without slipping in such a way ...

More Related Questions