Heron's+Formula

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This is Heron's Formula. You can use it to find the area of ANY triangle.

Take any traingle; let's use a right triangle so we know the area. How about 3-4-5? The area's six. Remember that, and we'll find it again using Heron's Formula.

First we find the semiperimeter, which is the sum of all the side lengths divided by two. In this case, it's 6, right? And side length A is 3, B is 4, and C is 5.

Use this drawing below. It helps when you can see it.



So √6(6-3)(6-4)(6-5) = √36 = 6

We got our answer!

Try it with any triangle! It always works!