Sofia cuts a piece of felt in the shape of a kite for an art project. The top two sides measure 20 cm each and the bottom two sides measure 13 cm each. One diagonal, [tex]\overline{EG}[/tex], measures 24 cm.

What is the length of the other diagonal, [tex]\overline{DF}[/tex]?

A. 5 cm
B. 16 cm
C. 21 cm
D. 32 cm



Answer :

To determine the length of the other diagonal ([tex]\(\overline{DF}\)[/tex]) in the kite, follow these steps:

1. Understand Kite Properties:
- In a kite, the diagonals are perpendicular (they intersect at right angles).
- The diagonals bisect each other.

2. Assign the given values:
- The length of diagonal [tex]\(\overline{EG}\)[/tex] is 24 cm.
- The top sides of the kite (legs of the kite) each measure 20 cm.
- The bottom sides each measure 13 cm.

3. Split the diagonals:
Since diagonals intersect perpendicularly and bisect each other, each half of diagonal [tex]\(\overline{EG}\)[/tex] will be:
[tex]\[ \overline{EG} = 24 \text{ cm} \quad \Rightarrow \quad \frac{\overline{EG}}{2} = 12 \text{ cm} \][/tex]

4. Form Right Triangles:
At the intersection of diagonals, four right-angled triangles are formed. Focus on one of the right-angled triangles that uses a 20 cm side, half of [tex]\(\overline{EG}\)[/tex] which is 12 cm, and half of the unknown diagonal ([tex]\(\overline{DF}\)[/tex]).

5. Using Pythagorean Theorem:
Let's denote half of [tex]\(\overline{DF}\)[/tex] as [tex]\(x\)[/tex]. Therefore, in a right triangle where:
- One leg is 12 cm (half of [tex]\(\overline{EG}\)[/tex])
- The hypotenuse is 20 cm (side of the kite)

The theorem states:
[tex]\[ 20^2 = 12^2 + x^2 \][/tex]
[tex]\[ 400 = 144 + x^2 \][/tex]
Solving for [tex]\(x\)[/tex]:
[tex]\[ x^2 = 400 - 144 \][/tex]
[tex]\[ x^2 = 256 \][/tex]
[tex]\[ x = \sqrt{256} \][/tex]
[tex]\[ x = 16 \][/tex]

6. Determine Full Length of [tex]\(\overline{DF}\)[/tex]:
Since [tex]\(x\)[/tex] represents half of [tex]\(\overline{DF}\)[/tex]:
[tex]\[ \overline{DF} = 2 \times x = 2 \times 16 = 32 \text{ cm} \][/tex]

Therefore, the length of the other diagonal, [tex]\(\overline{DF}\)[/tex], is 32 cm.

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