Question

3) How many diagonals can you draw from a single vertex in a 69-sided polygon? Why?

How many triangles do they make?

Answer 1

66 diagonals, 67 triangles

Explanation:

triangle - 0 diagonals(3-3), 1 triangle(3-2)

quadrilateral - 1 diagonal(4-3), 2 triangles(4-2)

pentagon 2 diagonal(5-3), 3 triangles (5-2)

hexagon 3 diagonals (6-3), 4 triangles (6-2)

n sides (n-3) diagonals, (n-2) triangles

69 sides 69-3 = 66 diagonals, 69-2 = 67 triangles