A curve which begins and ends at the same point is called a closed curve. Closed polygon in which all sides and angles are equal are called regular closed figures.
The length of the boundary of a figure is called its
The perimeter of a triangle is the sum of the lengths of the three sides, i.e., a + b + c.
The perimeter of an isosceles triangle = 2a + b and perimeter of an equilateral triangle = 3a.
The perimeter of a square is four times the length of its side, i, e., 4a.
The perimeter of act angle is twice the sum of its length and breadth, i.e., 2 (\[l\]+ b).
Perimeter is expressed in units of length.
Area of an enclosed plane is the number of square units that fit into it.