Aclub of twenty students wants to pick a three person subcommittee. how many ways can this be done?

Step-by-step explanation:

Combinations : If we want to choose items out of items, and order of the selection does not matter.

possible ways

Total number of students

Persons in subcommittee

Here order of selection does not matter, so we can use combination to get possible number of ways.

Number of ways

geometry: triangles

solvers

lessons

answers archive

call the larger triangle abc

then the smaller triangle cde is similar to abc (all angles are equal, aaa).  

ab is the side that is 36, and we wish to find de, the side corresponding to ab

area_cde = area_abc - area_cde --> area_abc / area_cde = 2

let x=length of de

ratio of areas = (ratio of sides)^2

+2+=+%2836%2fx%29%5e2+

+2+=+1296%2fx%5e2+

++x%5e2+=+1296%2f2+=+648+

25.45584