###### Key Takeaways

- The common formula for the area of a triangle is A = b × h / 2, where b is the base and h is the height.
- Other methods to calculate a triangle's area include using the lengths of two sides and the angle between them (A = a × b × sin(γ) / 2), two angles and the side between them, or the lengths of all three sides with Heron's formula.

It's inevitable. At some point in every math class, someone asks the teacher (usually with an exasperated groan), "When are we going to use any of this math?" In the case of area formulas, the answer is: all the time. Knowing area formulas, as in the examples below, comes in handy in everyday life.

Learning to calculate the areas of different shapes — or any closed geometric figure — has nearly infinite real-world applications. Whether you're designing your own greeting cards, searching for a rectangular area rug that perfectly fits with the table in your room, building a treehouse, or painting a fence, knowing how to calculate area, or the space enclosed in any shape, is endlessly practical.

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