Rectangle Perimeter Calculation: Finding the Distance Around a 4x5 Shape

Question

Calculate the perimeter of following rectangle:

AAABBBCCCDDD45

Video Solution

Solution Steps

00:00 Find the perimeter of the rectangle
00:03 Use the Pythagorean theorem in triangle ACD to find AD
00:15 Substitute appropriate values according to the given data and solve for AD
00:29 Isolate AD
00:50 This is the value of side AD
00:54 Opposite sides are equal in a rectangle
01:06 The perimeter of the rectangle equals the sum of its sides
01:16 Substitute appropriate values and solve for the perimeter
01:38 And this is the solution to the problem

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Identify the given information.
  • Step 2: Apply the Pythagorean theorem to find the missing side.
  • Step 3: Use the perimeter formula for rectangles.

Now, let's work through each step:

Step 1: The given information includes the base (AB=4 AB = 4 ) and the diagonal (AC=5 AC = 5 ).

Step 2: Apply the Pythagorean theorem. The diagonal acts as the hypotenuse of a right triangle with sides being the rectangle's base and height. Using the theorem:

(AB)2+(AD)2=(AC)2 (AB)^2 + (AD)^2 = (AC)^2

42+(AD)2=52 4^2 + (AD)^2 = 5^2

16+(AD)2=25 16 + (AD)^2 = 25

Solving for (AD)2 (AD)^2 :

(AD)2=2516=9 (AD)^2 = 25 - 16 = 9

Thus, AD=9=3 AD = \sqrt{9} = 3 .

Step 3: Calculate the perimeter using the formula for the perimeter of a rectangle:

P=2×(length+width) P = 2 \times (\text{length} + \text{width}) .

Inserting the values AB=4 AB = 4 and AD=3 AD = 3 :

P=2×(4+3)=2×7=14 P = 2 \times (4 + 3) = 2 \times 7 = 14 .

Therefore, the solution to the problem is 14 14 .

Answer

14