The word is heptagon. A heptagon has 7 sides and 7 corners. If you join corners by straight lines from one corner to another corner you will find 5 triangles, but if you join all corners to a point in the centre you will find 7 triangles. The Heptathlon in athletics is a contest in which the participants must compete in 7 different athletic forms of athletics.
9-2 = 7 triangles
A nine sided shape has 7 triangles
If only 7 are colinear, then the question implies the lines need not go through every point. In that case there is an infinity of lines for each point.
7
The word is heptagon. A heptagon has 7 sides and 7 corners. If you join corners by straight lines from one corner to another corner you will find 5 triangles, but if you join all corners to a point in the centre you will find 7 triangles. The Heptathlon in athletics is a contest in which the participants must compete in 7 different athletic forms of athletics.
A heptagon has 4 diagonal lines and 7 sides and it has 2 congruent diagonal lines and 2 congruent triangles
7 triangles
There are 7 triangles in a nonegon
It can have 5 triangles
9-2 = 7 triangles
A nine sided shape has 7 triangles
If only 7 are colinear, then the question implies the lines need not go through every point. In that case there is an infinity of lines for each point.
7
It can form 7 triangles
7
I get 9 triangle with fewer than 9 lines. Draw a square: ABCD (4 lines) Draw the diagonals AC, BD (2 lines) which meet at X in the centre. On a separate part of the page, draw triangle PQR (3 lines). That is 4 + 2 + 3 = 9 lines. The triangles are: ABC, BCD, CDA, DAB, AXB, BXC, CXD, DXA, and PQR 9 triangles with 9 lines. Could have done 13 triangles with 7 lines by drawing a line from A to BC.