Given 100 points with any 3 points non-aligned. Draw all the line passing through any 2 of these points. How many lines are there?

Given 100 points with any 3 points non-aligned. Draw all the line passing through any 2 of these points. How many lines are there?
 

given 5 points in which not any three points are collinear. Draw lines passing through the pair of points . How many lines are there?

Given 20 points. Draw the lines through the 2 points of these 20 points. How many lines are there if only 3 of 20 points are aligned?

Give 5 points which not any three points are collinear. Draw lines passing through the pair of points. How many lines are there?

Given two parallel lines xy & zt. Three points A,B & C are on line xy, two points D & E are on line zt. Draw lines passing through the pairs of points. How many lines are there? (including xy & zt) 

Given 20 points. Draw the lines through the 2 points of these 20 points. How many lines are there if only 3 of 20 points are aligned?
Answer: There are ...  lines.

Dịch: Cho 20 điểm. Vẽ đường đi qua 2 điểm trong số 20 điểm này. Có bao nhiêu đường nếu chỉ có 3 trong số 20 điểm đó thẳng hàng?
Trả lời: Có ... đường thẳng

True or false

1. we can draw many lines passing through 2 given points

2. we can draw many lines passing through 1 given point

3. we cannot draw any line passing through 3 given points

4. two different lines can only have 1 common point

5. three different lines cannot intersect at 1 point

6. we can draw 3 different lines from 3 collinear points

7. 2 parallel lines may have more than 1 common point