Find the number of sides of each of the two polygons if the total number of sides of the polygons is 13, and the sum of the number of diagonals of the polygons is 25.

Question

jack1 · Answer

apparently: number of diagonals in a polygon = 1/2 N(N-3)
and N = number of sides of 1 polygon
so call them a and b
a + b =13 sides total

1/2 a(a-3) + 1/2 b(b-3) = 25

jack1 · Answer

so simultaneous equations, rearrange one in terms of the other and sub it into the other equation

jack1 · Answer

so if a + b = 13
a = 13 - b

so now u can substitute (13-b) into the 2nd equation, wherever you see an "a".... im not 100% on this tho dude, let me know how u go, yeah?

jack1 · Answer

@klionmaster10 ...?

anonymous · Answer

Trying to solve.

anonymous · Answer

Thanks dude! I finally got it! :)

jack1 · Answer

sweet, what were ur answers if u dont mind me asking?

jack1 · Answer

octogon and 5 sided polygon?

anonymous · Answer

8 and 5

jack1 · Answer

niiiice! glad it worked ;S   slaters!