### Area of a rectangle

**Formula**: a * b = A (area)

**Example calculation:** 10cm * 3cm = ^{30cm2}

### Area of a square

**Formula**: a * a = A (area)

Example calculation**:** 5cm * 5cm = ^{25cm2}

### Area of a triangle

**Formula**: (a * h) / 2 = A (area)

Example calculation**:** (3cm * 5cm) / 2 = 7.^{5cm2}

### Area of a trapezoid

**Formula**: ((a c) * h) / 2 = A (area)

Example calculation**:** ((5cm 3cm) * 7cm) / 2 = ^{28cm2}

### Area of a parallelogram

**Formula**: a * ha = b * hb = A (area)

Example calculation**:** 5cm * 7cm = ^{35cm2}

### Area of a rhombus

**Formula**: a * ha = A (area)

Example calculation**:** 5cm * 7cm = ^{35cm2}

### Area of a deltoid

**Formula**: (e * f) / 2 = A (area)

Example calculation**:** (3cm * 5cm) / 2 = 7.^{5cm2}

### Area of a circle

**Formula**: Π * ^{r2} = A (area)

Π = 3.141592

Only 6 decimal places are displayed for Pi here.

**Example calculation:** Pi (Π) * ^{5cm2} = 78.^{54cm2}

Calculating the area is a central aspect of mathematics, especially in geometry. The area is defined as the amount of space occupied by a two-dimensional shape or figure. The specific formula for calculating the area varies depending on the type of figure.

1. **rectangle**: The area of a rectangle is calculated by multiplying the length by the width (A = length * width).

2. **square**: As all sides of a square are the same length, the area can be calculated by squaring the length of one side (A = side²).

3. **circle**: The area of a circle is calculated by multiplying the square of the radius by pi (approximately 3.14159) (A = pi * radius²).

4th **triangle**: The area of a triangle is calculated by multiplying the base by the height and then dividing by 2 (A = 0.5 * base * height).

These calculations are fundamental to many mathematical, scientific, engineering and construction applications. It is important to note that these formulas only apply to flat, two-dimensional shapes. For three-dimensional shapes such as cylinders, cubes or pyramids, other formulas are used to calculate the volume.