1. Overlap two long sides of a rectangle and two wide sides are on a straight line, thus forming a square. At this time, the side length of the square is 18 cm.

So the square area: 18× 18=324 (square centimeter).

The circumference of a square: 18×4=72 (cm).

A: The area of a square is 324 square centimeters, and the circumference of a square is 72 centimeters.

2. Overlap the wide sides of a rectangle, and the two long sides are on a straight line to form a rectangle. At this time, the length of the rectangle is 18+ 18=36 cm and the width is 9 cm.

So the area of the rectangle: 36×9=324 (square centimeter).

The circumference of a rectangle: 2×(36+9)=90 (cm).

A: The rectangle has an area of 324 square centimeters and a circumference of 90 centimeters.

Correlation formula of square

If S is the area of a square, L is the perimeter of the square, A is the side length of the square, and C is the diagonal of the square.

Then: s = a 2, l=4*a, c = √ 2 * a.

Properties of squares

(1) All four corners of a square are 90 degrees.

All four sides of a square are equal.

(3) The two diagonals of a square are equal in length and perpendicular to each other.