There are 8 straight lines on the plane.
No two straight lines are parallel and no 3 straight lines cross at 1 point.
How many pieces of intersection of these straight lines are there altogether?
Answer
28 pieces
Solution
When a set of 2 straight lines is chosen, 1 piece of intersection is made.
Answer
28 pieces
Solution
When a set of 2 straight lines is chosen, 1 piece of intersection is made.
Then the number of pieces of intersection is equal to the number of the case of choosing 2 straight lines among 8 lines.
