Calculating Area

Area measures the space inside a 2D shape, measured in square units (cm², m², ft², etc.).

Rectangle

$A = l \times w$

Example: Length 8, width 5 $A = 8 \times 5 = 40 \text{ square units}$

Square

$A = s^2$

Example: Side 6 $A = 6^2 = 36 \text{ square units}$

Triangle

$A = \frac{1}{2}bh$

Where $b$ = base and $h$ = height (perpendicular to base)

Example: Base 10, height 6 $A = \frac{1}{2}(10)(6) = 30 \text{ square units}$

Parallelogram

$A = bh$

Example: Base 8, height 4 $A = 8 \times 4 = 32 \text{ square units}$

Trapezoid

$A = \frac{1}{2}(b_1 + b_2)h$

Average the bases, multiply by height.

Circle

$A = \pi r^2$

Example: Radius 5 $A = \pi(5)^2 = 25\pi \approx 78.5 \text{ square units}$

Composite Shapes

For complex shapes:

1. Break into simpler shapes
2. Calculate each area
3. Add (or subtract) the areas