Answer:
The area of an octagon whose perimeter is 120 cm is 1086.4 
Step-by-step explanation:
An octagon is a polygon with eight sides. If the lengths of all the sides and the measurement of all the angles are equal, the octagon is called a regular octagon.
There is a predefined set of formulas for the calculation of perimeter, and area of a regular octagon.
The perimeter of an Octagon is given by

and the area of an Octagon is given by

We know that the perimeter is 120 cm, solving for side length (a) in the perimeter formula we get

Now, we calculate the area

1/9 on a calculator is 0.11111111
Answer:
9 Sides
Step-by-step explanation:
According to the Question,
- Given That, The sum of the interior angles(s), in an n-sided polygon can be determined using the formula s=180(n−2), where n is the number of sides
Therefore, The sides do a polygon have if the sum of the interior angles is 1,260°.
Put The Values in Formula, we get
1260=180(n−2)
n-2 = 7
n=9 (9 Sides)
2/3 x 3/4 =6/12=1/2
(Multiply numerators, multiply denominators, simplify)
Triangles add to 180° and there is already 100° shown inside of the triangle (30° plus 70° = 100°). 180° -100° = 80°, which is x. X and y are vertical angles, so y is also 80°. The answer is B.