Rectangle Perimeter: Calculate ABCD with Equal Segments CE and AB

Question

Look at the following rectangle:

AAABBBCCCDDDFFFEEE31117

CE = AB

Calculate the perimeter of rectangle ABCD.

Video Solution

Solution Steps

00:06 Let's calculate the perimeter of rectangle, A. B. C. D.
00:10 Remember! Opposite sides are equal in a rectangle.
00:17 For segment F. C., it's the entire side B. C. minus segment B. F.
00:23 Now, plug in the given values to find F. C. and solve it step by step.
00:37 Great job! That's the height, F. C.
00:41 Next, use the Pythagorean theorem on triangle F. C. E. to find C. E.
00:51 Again, insert the values into the formula, and solve for C. E.
01:08 Let's isolate C. E. You're doing great!
01:27 Nice work! That's the length of side C. E.
01:32 According to the data, sides are equal. Keep this in mind.
01:41 And remember, opposite sides are always equal in a rectangle.
01:54 The perimeter is simply the sum of all sides.
01:58 Plug in the values and solve for the perimeter. Almost there!
02:21 Awesome! That's the solution. Well done!

Step-by-Step Solution

Since in a rectangle every pair of opposite sides are equal to each other, we can claim that:

AD=BC=11 AD=BC=11

We can calculate side FC:

113=FC 11-3=FC

8=FC 8=FC

Let's focus on triangle FCE and calculate side CE using the Pythagorean theorem:

CF2+CE2=FE2 CF^2+CE^2=FE^2

Let's substitute the known values into the formula:

82+CE2=172 8^2+CE^2=17^2

64+CE2=289 64+CE^2=289

CE2=28964 CE^2=289-64

CE2=225 CE^2=225

Let's take the square root:

CE=15 CE=15

Since CE equals AB and in a rectangle every pair of opposite sides are equal to each other, we can claim that:

CE=AB=CD=15 CE=AB=CD=15

Now we can calculate the perimeter of the rectangle:

11+15+11+15=22+30=52 11+15+11+15=22+30=52

Answer

52