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11. Find x, y, and z.
5
y
6
3

11. Find x, y, and z. 5 y 6 3-example-1
User Iscream
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1 Answer

4 votes

Answer:

  • x = z = 3√5
  • y = 4

Explanation:

You want the missing segment lengths in the kite shown, where half-diagonals are 3 and 6, and one side length is 5.

Kite

The diagonals of a kite cross at right angles, so each of the triangles shown is a right triangle. The figure has left-right symmetry about the vertical axis, so x=z.

Length y

We recognize the top triangles as being 3-4-5 right triangles, so the missing side length is y = 4.

Lengths x and z

These lengths are the hypotenuse of a right triangle with legs 3 and 6. The Pythagorean theorem tells us they are ...

x² = 3² +6²

x² = 9 +36 = 45

x = √(45) = √(9·5) = 3√5

The lengths x and z are ...

x = z = 3√5

__

Additional comment

In case you have never heard of a 3-4-5 right triangle, you can find y from the Pythagorean relation:

5² = 3² +y²

y² = 25 -9 = 16

y = √16 = 4

The {3, 4, 5} Pythagorean triple is one of several in common use in algebra, trig, and geometry problems. Others include {5, 12, 13}, {7, 24, 25}, {8, 15, 17}.

User Journeyer
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