The perimeter of a triangle is the sum of all side lengths of the triangle. The numerical expression for the perimeter of Stephanie's triangle is: 
Let the sides of Juan's triangle be x, y and z. So:

The perimeter (J) of Juan's triangle is calculated by adding all sides.
So:

This gives:


From the question, we understand that:
The perimeter (S) of Stephanie's triangle is half that of Juan.
This means that:

Substitute 25 for J

Hence, the numerical expression for the perimeter of Stephanie's triangle is: 
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Answer:
The length of the rectangle is 13 inches and its width (13 + 12) is 25 inches.
Step-by-step explanation:
You have to consider the formula of the perimeter = 2·length + 2·width.
If we call "x" to the length ⇒ width = x + 12 .
Perimeter = 2x + 2·(x + 12) ⇒ Perimeter = 2x + 2x + 24
⇒Perimeter = 4x + 24. ⇒ 76 = 4x + 24 ⇒ 76 - 24 = 4x ⇒52 = 4x
⇒ 52/4 = x ⇒ x = 13.
So, the length of the rectangle is 13 inches and its width (13 + 12) is 25 inches.
Answer: x=-2+2 sqrt 6 divided by 5
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Step-by-step explanation: