input: Write a python function to calculate the area of an n-sided regular polygon.
  assert calculate_area(3) == 0.43
  assert calculate_area(4) == 1.0
  assert calculate_area(5) == 1.72
output: import math
  
  def calculate_area(n):
      return round((n * math.sin(2 * math.pi / n)) / 2, 2)