# What is the perimeter of the square

### Chocolate bars and their area

Jana and Tarek like to eat chocolate. Jana prefers a variety that looks like a square from above. The sides are all 12 cm long. The Tarek variety is a 16 cm long and 9 cm wide rectangle when viewed from above.

How big are the area and perimeter? Both areas can be divided into centimeter squares. To find the number of all small squares, you can count them all. Then you have that Area. Or you just take the length and width times:

Square: \$\$12*12=144\$\$

Rectangle: \$\$9*16=144\$\$

Mathematically exactly with the units of measurement:

Square: \$\$ 12 cm * 12 cm = 144 cm ^ 2 \$\$

Rectangle: \$\$ 9 cm * 16 cm = 144 cm ^ 2 \$\$

The measure for the area is always square centimeters, square meters, etc.

A square is also a rectangle.

### Calculate area You designate the sides of a square with small letters: \$\$ a \$\$, \$\$ b \$\$, \$\$ c \$\$, \$\$ d \$\$.

If two or more sides exactly the same length you can each same letter use.

This is the general formula for the area of ​​rectangles:

\$\$ A = a * b \$\$

### Special formula for squares

Because with the square all Sides are the same length, you can use this formula for squares:

\$\$ A = a * a \$\$

or summarized:

\$\$ A = a ^ 2 \$\$

The length a and the width b can be called. But it also works the other way around.

The capital A stands for the English word "area". The F has already been assigned to other formulas.

### Calculate sizes

To the scope To find a rectangle or a square, you simply add up all the sides:

Square: \$\$12+12+12+12=48\$\$

Rectangle: \$\$9+16+9+16=50\$\$

Or more precisely with the units of measurement:

Square: \$\$ 12 cm + 12 cm + 12 cm + 12 cm = 48 cm \$\$

Rectangle: \$\$ 9 cm + 16 cm + 9 cm + 16 cm = 50 cm \$\$

### General formula

The following applies to all quadrilaterals:

\$\$ u = a + b + c + d \$\$

Because not all sides of rectangles and squares are of different lengths, you can simplify the formula:

Rectangle:

\$\$ u = a + a + b + b = 2 * a + 2 * b \$\$

Square:

\$\$ u = a + a + a + a = 4 * a \$\$

Both chocolates cover an area of ​​\$\$ 144 \$\$ \$\$ cm ^ 2 \$\$, the circumference of Jana's chocolate is \$\$ 48 \$\$ \$\$ cm \$\$, and the chocolate from Tarek has a circumference of \$\$ 50 \$\$ \$\$ cm \$\$. The measure for the circumference is always centimeters, meters, ... So the normal measure of length.

Scope = sum of all pages

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### Finally:

What do square and rectangle have in common, what are the differences between them?

• Both have four equal (right) angles of 90 ° each.

• The opposite sides are the same length for both.

• But just in the case of a square, all four sides are the same length.

A square is so a rectangle, and a rectangle can be a square.