# geometry

posted by .

distint points a, b, c, d, e, and f are marked on a circle. How many triangles can be formed using these points as vertices?

• geometry -

Draw a circle, form as many triangles as you can, and count.

• geometry -

ok i tried that that its hard why don't u try and tellme the answer ?

• geometry -

You have 6 points on a circle.
It is not possible to have 3 of them forming a straight line (not a triangle) so the question becomes how many choices are there of 3 elements form 6
or C(6,3) = 6!/(3!3!) = 20

## Similar Questions

1. ### math

the number of noncollinear points needed to determine a circle Two. The location of the center, and one point on the circle (ie, the length of radius), you have determined the circle. However, the circle thus determined can be an an …
2. ### Math: Combinations

There are 20 points all in one straight line and 15 others in a parallel line. How many possible triangles having these points as vertices can be formed?

A Rectangle with vertices A B C AND D. The triangle is divided with vertices P AND Q. How many right triangles can you make with using only three of the vertices {A B C D P OR Q}. AND also the answer for this question is not 12 or …
4. ### math- algebra- help please!

12 points lie on a circumference of a circle how many inscribed triangles can be constructed having 3 vertices?
5. ### math

There are nine points on a piece of paper. No three of the points are collinear. How many different triangles can be formed by using three of the nine points as vertices?
6. ### analytic geometry/graphing problem

The vertices of a triangle are the points of intersection of the line y=-x-1, x=2 and y = 1/5x + 13/5. Find an equation of the circle passing through all three vertices. I don't understand how to solve this: should I set them all equal …
7. ### Geometry

Let A be a convex 61− gon. We then place n points {x i} n i=1 in the interior of A . What is the minimum number n , such that the interior of any triangle, whose vertices are also vertices of A , will contain at least one of …
8. ### Geometry

Which one of these is NOT a step used when constructing an inscribed square using technology?
9. ### Math

Six points lie on the circumference of a circle. How many different triangles can be drawn having some of these points as vertices?