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A Leg That Is Not Whole

Part of the Triangles section of Coddy's Geometry journey. Lesson 38 of 71.

A leg can come out as a root, just as a hypotenuse can. With hypotenuse 7 and leg 2:

A right triangle with hypotenuse 7, one leg 2 and the other leg a unknown

Hypotenuse 7, leg 2

a = √(7^2 - 2^2) = √(45)

a = 3√(5)

45 has the square factor 9, so the root simplifies to 3√(5). 3√(5) is about 6.7, which is a little less than the hypotenuse 7, as a leg must be.

When the number under the root has no square factor, the root is the finished answer. Hypotenuse 6 and leg 1 give √(35). The rules for roots from the hypotenuse chapter are the same here. The only difference is that the squares are subtracted instead of added.

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Challenge

A right triangle has hypotenuse 8 and one leg 3.

A right triangle with hypotenuse 8, one leg 3 and the other leg b unknown

Find the other leg b exactly.

Try it yourself

b = sqrt(8^2 - 3^2)

Solve for b

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This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Triangles