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### How to Calculate the Area of a Parallelogram, Kite, or Trapezoid

The area formulas for the parallelogram, kite, and trapezoid are based on the area of a rectangle. The following figures show you how each of these three quadrilaterals relates to a rectangle, and the [more…]

### A Rhombus Area Problem

Here’s a rhombus area problem involving triangles and ratios: Find the area of rhombus *RHOM* given that *MB*is 6 and that the ratio of *RB* to *BH* is 4 : 1, as shown in the following figure. [more…]

### How to Calculate the Area of a Kite

You calculate the area of a kite by using the lengths of its diagonals. Here’s an example: what’s the area of kite *KITE* in the following figure? [more…]

### How to Calculate the Area of a Trapezoid

You can use the right-triangle trick to find the area of a trapezoid. The following trapezoid *TRAP* looks like an isosceles trapezoid, doesn’t it? Don’t forget — looks can be deceiving. [more…]

### How to Calculate the Area of a Regular Octagon

You can calculate the area of a regular octagon with the standard regular polygon method, but there’s a nifty alternative method based on the fact that a regular octagon is a square with its four corners [more…]

### Interior and Exterior Angles of a Polygon

Everything you need to know about a polygon doesn’t necessarily fall within its sides. You may need to find exterior angles as well as interior angles when working with polygons: [more…]

### How to Find the Number of Diagonals in a Polygon

To find the number of diagonals in a polygon with *n*sides, use the following formula: [more…]

### How to Calculate the Area of a Quadrilateral

There are five formulas that you can use to calculate the area of the seven special quadrilaterals. There are only five formulas because some of them do double duty — for example, you can calculate the [more…]

### How to Calculate the Area of a Regular Polygon

A *regular polygon* is equilateral (it has equal sides) and equiangular (it has equal angles). To find the area of a regular polygon, you use an *apothem* — a segment that joins the polygon’s center to the [more…]

### How to Calculate the Area of a Regular Hexagon

One way to find the area of a regular hexagon is by first dividing it into equilateral triangles. You also need to use an *apothem* — a segment that joins a regular polygon’s center to the midpoint of any [more…]