Introduction to Quadrilateral Perimeters and Areas
Interior area is an expression of the size of the region enclosed by a polygon, and that lies in the same plane as all the vertices of the polygon. It is expressed in square units (or units squared). The perimeter of a polygon is the sum of the lengths of its sides. Perimeter can also be defined as the distance once around a polygon, starting at some point on one of its sides and proceeding clockwise or counterclockwise along the sides until that point is encountered again. Perimeter is expressed in linear units (or, if you prefer, “plain old units”).
Perimeter Of Parallelogram
Suppose we have a parallelogram defined by points P, Q, R , and S , with sides of lengths d and e as shown in Fig. 315. The two angles labeled x have equal measure. Let d be the base length and let h be the height. Then the perimeter, B , of the parallelogram is given by the following formula:
B = 2 d + 2 e
Interior Area Of Parallelogram
Suppose we have a parallelogram as defined above and in Fig. 315. The interior area, A , is the product of the base length and the height:
A = dh
Perimeter and Area of a Rhombus
Perimeter Of Rhombus
Suppose we have a rhombus defined by points P, Q, R , and S , and having sides all of which have the same length. The rhombus is a special case of the parallelogram (Fig. 315) in which d = e . Let the lengths of all four sides be denoted d . The perimeter, B , of the rhombus is given by the following formula:
B = 4 d
Interior Area Of Rhombus
Suppose we have a rhombus as defined above and in Fig. 315, where d = e . Let the lengths of all four sides be denoted d . The interior area, A , of the rhombus is the product of the length of any side and the height:
A = dh
Perimeter and Area of a Rectangle
Perimeter Of Rectangle
Suppose we have a rectangle defined by points P, Q, R , and S , and having sides of lengths d and e as shown in Fig. 316. Let d be the base length, and let e be the height. The perimeter, B , of the rectangle is given by the following formula:
B = 2 d + 2 e
Interior Area Of Rectangle
Suppose we have a rectangle as defined above and in Fig. 316. The interior area, A , is given by:
A = de
Perimeter and Area of a Square
Perimeter Of Square
Suppose we have a square defined by points P, Q, R , and S , and having sides all of which have the same length. The square is a special case of the rectangle (Fig. 316) in which d = e . Let the lengths of all four sides be denoted d . The perimeter, B , of the square is given by the following formula:
B = 4 d
Interior Area Of Square
Suppose we have a square as defined above and in Fig. 316, where d = e . Let the lengths of all four sides be denoted d . The interior area, A , is equal to the square of the length of any side:
A = d ^{2}

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