Question 2209
to find the sum of the interior angles, yes that formula is correct, but can you remember it? Do you understand it?

A much better method is NOT to remember that formula, but to understand what i tell you here.....

a triangle has 3 sides...angles=180
any 4-sided figure can be split into 2 triangles...so 2 triangles = 2*180
any 5-sided figure can be split into 3 triangles...so 3 triangles = 3*180

blah blah blah...

any 24-sided figure can be split into 22 triangles...so 22 triangles = 22*180 etc. See? Now this explains the formula, doesn't it? 

eg what is the sun of the interior angles of a 16 sided figure?

Answer... well, a 16-sided figure can be split into 14 triangles, so 14*180 = whatever :-). See, no formula required, ever!


jon