Question

HELP PLEASE :(
suppose that 19 points are drawn in the plane such that exactly 7 are collinear. find:
a. the number of straight lines which pass through at least 2 of the 19 points.
b. the number of triangles whose vertices are 3 of the 19 points.

Answer 1

I would choose option A.

Answer 2

it's not a multiple choice question.

Answer 3

when one says exactly 7 are collinear, these form a line right?? then the rest of the 12 points are scattered around?

Answer 4

yes

Answer 5

Do you always seek confirmation with your teacher before writing down the solution? If so, that is a bad habit that you must get rid of. Only check your solution after you have TRIED.

Answer 6

i think it is B. but i'm not sure

Answer 7

Do you always seek confirmation with your teacher before writing down the solution? - no, i don't. and i always try many times before posting a question here, okay?

@danyaennim it's not a multiple choice question.

Answer 8

ans to a) is 19c7 where c is combination

Answer 9

@prakash3705 please explain how you came up with 19C7 and what's your reasoning? because isn't it that any of those 7 collinear lines and another point from the 12 remaining that aren't collinear can still make a line? i'm really confused.

Answer 10

@ParthKohli , @UnkleRhaukus , @dumbcow , @Callisto , @sauravshakya , @precal @radar , @ganeshie8 etc. please help! :( i'm really confused.