interior angle of a regular 18-gon.
It is easier to calculate the exterior angle of a regular polygon of n-sides (n-gon) by the relation
exterior angle = 360/n
For a 18-gon, n=18, so exterior angle = 360/18=20 °
The value of each interior angle is therefore the supplement, or
Interior angle = 180-20=160 degrees.
Naming of a 9-gon
A polygon with 9 vertices is called a nonagon (in English) or enneagon (French ennéagone, but the English version is sometimes used)
You had a good start with the correct answer.
Exterior angle of a 15-gon
The exterior angle of a 15-gon can be calculated using the relation given in the first paragraph, namely
Exterior angle = 360/15=24 degrees
Answer: x = 12
Step-By-Step: 180 - 100 = 80
Step-By-Step: 80 - 12 = 68
Step-By-Step: 68 is angle ( X + 12)
68 + 12 = 80 + 100 equals 180
I would say the third asnwer, so 90 degrees :)
Answer: 0.8
Step-by-step explanation:
