maths
posted by polygon on .
each interior angle of a regular polygon is 18 degree more than eight times an exterior angle. the number os sides of polygon is.

at each vertex, interior + exterior = 180 degrees.
If exterior = x,
x+(8x+18) = 180
9x = 162
x = 18
he exterior angle of a regular ngon is 360/n, so
18 = 360/n
n = 20 
Interior angle = 180  (exterior angle) = 180 360/N
Exterior angle = 360/N
180  (360/N) = [8*360/N] +18
9*360/N = 162
N = 20 sides
It is called an icosagon