Similar Triangles in Rectangle ABCD: Calculate Perimeter Using 16, 8, and 10

Question

AAABBBCCCDDDEEEFFF16810

ΔADEΔFCE ΔADE∼Δ\text{FCE}

Calculate the perimeter of the given rectangle ABCD.

Video Solution

Solution Steps

00:00 Find the perimeter of rectangle ABCD
00:03 We'll use the Pythagorean theorem in triangle EFC
00:08 We'll substitute appropriate values and solve for FC
00:14 Let's isolate FC
00:20 And this is the length of FC
00:26 The triangles are similar according to the given information, let's find the similarity ratio
00:33 We'll divide a side in one triangle by its corresponding side in the second triangle
00:46 Now let's substitute appropriate side values to find the ratio
00:58 We'll multiply by 6 and get the length of AD
01:03 This is the length of side AD, now we can calculate the rectangle's perimeter
01:07 Opposite sides are equal in a rectangle
01:14 The side equals the sum of its parts
01:18 The perimeter of the rectangle equals the sum of its sides
01:22 Therefore, let's substitute the side values and add them to find the perimeter
01:26 And this is the solution to the problem

Step-by-Step Solution

Let's look at triangle FCE and calculate side FC using the Pythagorean theorem:

EC2+FC2=EF2 EC^2+FC^2=EF^2

Let's substitute the known values into the formula:

82+FC2=102 8^2+FC^2=10^2

64+FC2=100 64+FC^2=100

FC2=10064 FC^2=100-64

FC2=36 FC^2=36

Let's take the square root:

FC=6 FC=6

Since we know that the triangles overlap:

ADFC=DECE=AEFE \frac{AD}{FC}=\frac{DE}{CE}=\frac{AE}{FE}

Let's substitute the known values into the formula:

AD6=168 \frac{AD}{6}=\frac{16}{8}

AD=2×6=12 AD=2\times6=12

Let's calculate side CD:

16+8=24 16+8=24

Since in a rectangle each pair of opposite sides are equal, we can calculate the perimeter of rectangle ABCD

12+24+12+24=24+48=72 12+24+12+24=24+48=72

Answer

72