How to Calculate a Right Triangle
As with all triangles, right triangles are constructed of three connected sides and three angles between the sides. What makes right triangles special is that, by definition, one of those angles is a right or 90-degree angle, just like the corner of a box. Because of this we can use a standard formula, the Pythagorean Theorem, to calculate the length of the triangle's slanted (longest) side, which is known as the hypotenuse, if we know the length of the other two sides. Also, the standard formula for calculating a triangle's area (base times height, all divided by 2) still applies to right triangles.
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Instructions
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Area
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1
Measure or calculate the length of the triangle's legs on either side of the right angle.
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2
Multiply the length of these two sides together. For example, if the triangle's legs on either side of the right angle measure 3 and 4 inches respectively, we have 3 * 4 = 12 inches.
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3
Divide the result from Step 2 by 2 to get the triangle's area. To continue our example, we have 12 / 2 = 6 inches.
Hypotenuse
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4
Calculate or measure the lengths of the triangle's legs on either side of the right angle. Square each one of them. To borrow our example triangle from the previous section, we would have 3 inches squared = 3 * 3 = 9 inches and 4 inches squared = 4 * 4 = 16 inches.
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5
Add together the two results from the previous step. We have 9 + 16 = 25.
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6
Take the square root of the result from Step 2. This is the length of the triangle's other side, the hypotenuse. You may need a calculator for this operation; in the case of our example, the result is relatively easy to find since the square root of 25 is 5. So the length of the example triangle's hypotenuse is 5 inches.
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