Charlene puts together two isosceles triangles so that they share a base, creating a kite. The legs of the triangles are 10 inches and 17 inches, respectively. If the length of the base for both triangles is 16 inches, what is the length of the kite's other diagonal?

A. 6 inches
B. [tex]$4 \sqrt{21}$[/tex] inches
C. [tex]$16 \sqrt{21}$[/tex] inches
D. 21 inches



Answer :

Sure! Let's break down the given problem step-by-step to find the length of the kite's other diagonal.

### Step 1: Understand the Problem
Charlene has created a kite by joining two isosceles triangles along their bases. The triangles have the following properties:
- The legs of the first triangle are 10 inches each.
- The legs of the second triangle are 17 inches each.
- The common base for both triangles is 16 inches long.

### Step 2: Identify Necessary Elements
We need to determine the length of the kite's other diagonal. To calculate this, we must find the height of each isosceles triangle relative to the base.

### Step 3: Calculate Heights of Triangles
Since the base of both triangles is 16 inches, the height can be calculated by dropping a perpendicular from the apex of each triangle to the midpoint of the base (which is 8 inches from either end of the base).

#### Height of the First Triangle (Legs = 10 inches, Base = 16 inches):
- Given legs: \(10 \) inches
- Half of the base: \( 16 / 2 = 8 \) inches

Using the Pythagorean theorem in the right triangle:
[tex]\[ ( \text{Leg} )^2 = (\text{Height})^2 + (\text{Half Base})^2 \][/tex]
[tex]\[ 10^2 = \text{Height}^2 + 8^2 \][/tex]
[tex]\[ 100 = \text{Height}^2 + 64 \][/tex]
[tex]\[ \text{Height}^2 = 100 - 64 \][/tex]
[tex]\[ \text{Height}^2 = 36 \][/tex]
[tex]\[ \text{Height} = 6 \, \text{inches} \][/tex]

#### Height of the Second Triangle (Legs = 17 inches, Base = 16 inches):
- Given legs: \(17 \) inches
- Half of the base: \( 16 / 2 = 8 \) inches

Using the Pythagorean theorem in the right triangle:
[tex]\[ ( \text{Leg} )^2 = (\text{Height})^2 + (\text{Half Base})^2 \][/tex]
[tex]\[ 17^2 = \text{Height}^2 + 8^2 \][/tex]
[tex]\[ 289 = \text{Height}^2 + 64 \][/tex]
[tex]\[ \text{Height}^2 = 289 - 64 \][/tex]
[tex]\[ \text{Height}^2 = 225 \][/tex]
[tex]\[ \text{Height} = 15 \, \text{inches} \][/tex]

### Step 4: Calculate Length of the Kite's Other Diagonal
The kite's other diagonal is the sum of the heights of the two triangles:
[tex]\[ \text{Height of the first triangle} + \text{Height of the second triangle} \][/tex]
[tex]\[ 6 \, \text{inches} + 15 \, \text{inches} = 21 \, \text{inches} \][/tex]

### Final Answer
The length of the kite's other diagonal is \( 21 \) inches. Hence, the correct choice is:

[tex]\[ \boxed{21 \, \text{inches}} \][/tex]

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