How are the area formulas for triangles parallelograms and trapezoidal related to the area of a rectangle?

The area formulas for triangles, parallelograms, and trapezoids are derived from the area of a rectangle, as they can be thought of as derived shapes. The area of a rectangle is calculated as base times height (A = base × height). For a triangle, the area is half that of a rectangle with the same base and height (A = 1/2 × base × height). A parallelogram retains the rectangle's base and height relationship (A = base × height), while a trapezoid can be viewed as a rectangle with two triangles removed or added, leading to its area formula (A = 1/2 × (base1 + base2) × height).