en.wikipedia.org/wiki/Heron%27s_formula

In geometry, Heron's **formula** (sometimes called Hero's **formula**), named after
Hero of Alexandria, gives the **area** of a triangle by requiring no arbitrary choice of
side as base or vertex as origin, contrary to other **formulas for the area** of a
triangle, .... The **formula** is credited to Heron (or Hero) of Alexandria, and a **proof**
can be ...

www.basic-mathematics.com/proof-of-the-area-of-a-trapezoid.html

Find here a nifty **proof** of the **area of a trapezoid** using some basic math concepts.
... Average base of a trapezoid shown in red. Then, make 4 triangles as shown
below: Trapezoid turned into a rectangle ... **Formula** of the **area of a trapezoid** ...

www.mathopenref.com/trapezoidareaderive.html

This page describes **how to derive** the forumula for the **area of a trapezoid**, by
creating a parallelogram from two congruent trapezoids. The **equation** is then ...

illuminations.nctm.org/Lesson.aspx?id=1893

The main portion of this lesson involves the **derivation** of an **area formula** for
**trapezoids**. Prior to that, allow students some exploration time. Ask them to
suggest ...

www.mathsteacher.com.au/year8/ch12_area/04_trap/trap.htm

Finding a **formula for the area of a trapezium** and applying this to problems.

www.khanacademy.org/math/basic-geo/basic-geo-area-and-perimeter/area-trap-composite/v/area-of-a-trapezoid-1

**Area of a trapezoid** is found with the **formula**, A=(a+b)/2 x h. Learn how to use the
**formula** to find area of trapezoids.

solvemymaths.com/2015/03/07/proof-area-of-a-trapezium-trapezoid-us

Mar 7, 2015 **...** At the Don Steward event last weekend, Don demonstrated how the **formula** for a
**trapezium** can be derived in different ways. He asked the ...

proofsfromthebook.com/2013/02/23/area-of-a-trapezoid

Feb 23, 2013 **...** In this post, we **derive** the **area of a trapezoid**. We use the fact that a trapezoid
can be partitioned into two triangles and one rectangle. The area ...