Posted by **karen** on Sunday, February 10, 2013 at 7:45pm.

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 ?

- math -
**Reiny**, Sunday, February 10, 2013 at 9:23pm
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

- math -
**karen**, Monday, February 11, 2013 at 9:01am
thanks for your kindness

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