Question

a diagonal of a polygon is a straight line joining any 2 non-adjacent corners.a decagon has 10 corners. .how many diagonals does it have ?

Answer 1

Joining any two points will produce a line
there are C(10,2) such lines or 45 of them
But, 10 of them will be the actual sides of the polygon, the others are diagonals

number of diagonals = 45-10 = 35

Answer 2

thanks for your kindness