Solve for X: Rectangle with Perimeter 48 and Dimensions (3-x) and (8+2x)

Question

The rectangle below is composed of two smaller rectangles.

Calculate x given that the perimeter of rectangle ABCD is 48.

AAABBBCCCDDDEEEFFF5+x3-x8+2x

Video Solution

Solution Steps

00:05 Let's find the value of X in the rectangle.
00:09 Remember, opposite sides are equal in a rectangle.
00:14 The whole side equals the sum of its parts.
00:18 So, let's plug in the values we know to find the side length.
00:27 Great! This is the side length of the rectangle.
00:33 Now, the perimeter is the total of all the sides added up.
00:40 Insert the known perimeter value, according to the information we have, to solve for X.
00:47 Let's gather all the like terms together.
00:50 We need to get X by itself now.
00:53 And that's how we solve this problem! Well done!

Step-by-Step Solution

To solve the problem of finding x x given the perimeter of rectangle ABCD, we follow these steps:

  • Step 1: The problem states that the perimeter of rectangle ABCD is 48. The expressions related to x x represent sides of this rectangle.
  • Step 2: Identify the sides using expressions in the diagram:
    • The complete top and bottom sides (width) are divided into 3x 3-x and full vertical is 5+x 5+x .
    • One vertical height is 8+2x 8+2x .
  • Step 3: Use the perimeter formula for a rectangle: P=2(width+height) P = 2(\text{width} + \text{height}) .
  • Step 4: Substitute in the formula and solve for x x .

Now, let's apply these steps:

Express the perimeter using the given: 2((3x)+(5+x))+2(8+2x)=48 2((3-x) + (5+x)) + 2(8+2x) = 48 .

Simplify the equation:

2(3x+5+x)+2(8+2x)=48 2(3-x + 5+x) + 2(8+2x) = 48

2(8)+2(8+2x)=48 2(8) + 2(8+2x) = 48

16+16+4x=48 16 + 16 + 4x = 48

Combine like terms:

32+4x=48 32 + 4x = 48

Isolate 4x 4x :

4x=4832 4x = 48 - 32

4x=16 4x = 16

Solve for x x :

x=164 x = \frac{16}{4}

x=4 x = 4

Therefore, the value of x x is x=4 x = 4 .

Answer

4