Perimeter of a trapezoid

The trapezoid is a quadrilateral defined as having 2 parallel opposite sides. The calculation of the perimeter of the trapezoid is solved using a very simple formula that we will see below: all sides are added together. This type of questions can appear in tests of the first and second level in the first years of high school and also in final exams of level 3, 4 and 5 for the graduation of the secondary cycle.

A1- The_calculation_of_the_perimeter_of_the_trapezoid.

Suggested Topics to Practice in Advance

  1. Area
  2. Trapezoids
  3. Area of a trapezoid
  4. Areas of Polygons for 7th Grade
  5. Area of a right-angled trapezoid
  6. Area of an isosceles trapezoid
  7. How do we calculate the area of complex shapes?

Practice Perimeter of a Trapezoid

Examples with solutions for Perimeter of a Trapezoid

Exercise #1

What is the perimeter of the trapezoid in the figure?

444555999666

Video Solution

Step-by-Step Solution

To find the perimeter we will add all the sides:

4+5+9+6=9+9+6=18+6=24 4+5+9+6=9+9+6=18+6=24

Answer

24

Exercise #2

Look at the trapezoid in the diagram.

101010777121212777

What is its perimeter?

Video Solution

Step-by-Step Solution

In order to calculate the perimeter of the trapezoid we must add together the measurements of all of its sides:

7+10+7+12 =

36

And that's the solution!

Answer

36

Exercise #3

Calculate the perimeter of the trapezoid below:

999555121212444

Step-by-Step Solution

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

  • Step 1: Identify the given side lengths of the trapezoid.
  • Step 2: Use the perimeter formula for a trapezoid, which is the sum of the lengths of its sides.
  • Step 3: Perform the necessary addition to compute the perimeter.

Now, let's work through each step:
Step 1: The trapezoid has side lengths of 99, 55, 1212, and 44.
Step 2: The formula for the perimeter PP of a trapezoid is:
P=side1+side2+side3+side4 P = \text{side}_1 + \text{side}_2 + \text{side}_3 + \text{side}_4
Step 3: Plugging in the values, we compute:
P=9+5+12+4 P = 9 + 5 + 12 + 4
Step 4: Calculating the sum:
P=30 P = 30

Therefore, the perimeter of the trapezoid is 3030.

Answer

30

Exercise #4

Calculate the perimeter of the trapezoid below:

161616161616111151515

Step-by-Step Solution

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

  • Identify the given side lengths of the trapezoid.
  • Apply the formula for the perimeter of a trapezoid.
  • Perform the addition of all side lengths to calculate the perimeter.

Let's work through each step:

Step 1: Identify the given side lengths. The trapezoid has:

  • Top base: a=16 a = 16
  • Bottom base: b=1 b = 1
  • Non-parallel side: c=15 c = 15
  • Other non-parallel side: d=16 d = 16

Step 2: We'll use the formula for the perimeter of a trapezoid:

P=a+b+c+d P = a + b + c + d

Step 3: Plug in the values and perform the calculation:

P=16+1+15+16 P = 16 + 1 + 15 + 16

P=48 P = 48

Therefore, the perimeter of the trapezoid is 48 48 .

Answer

48

Exercise #5

Calculate the perimeter of the trapezoid below:

101010111111555101010

Step-by-Step Solution

To solve this problem, we'll calculate the perimeter of the trapezoid by summing the lengths of its sides:

  • Step 1: Identify the side lengths of the trapezoid:
    Top side =10 = 10 , Bottom side =5 = 5 , Left side =10 = 10 , Right side =11 = 11 .
  • Step 2: Apply the perimeter formula:
    The formula for the perimeter P P of a trapezoid is P=a+b+c+d P = a + b + c + d .
  • Step 3: Perform the calculations:
    Substitute the given lengths into the formula:
    P=10+5+10+11=36 P = 10 + 5 + 10 + 11 = 36 .

Therefore, the perimeter of the trapezoid is 36 36 .

Answer

36

Exercise #6

Look at the trapezoid in the figure.

The long base is 1.5 times longer than the short base.

Find the perimeter of the trapezoid.

222333555

Video Solution

Step-by-Step Solution

First, we calculate the long base from the existing data:

Multiply the short base by 1.5:

5×1.5=7.5 5\times1.5=7.5

Now we will add up all the sides to find the perimeter:

2+5+3+7.5=7+3+7.5=10+7.5=17.5 2+5+3+7.5=7+3+7.5=10+7.5=17.5

Answer

17.5

Exercise #7

The perimeter of the trapezoid in the diagram is 25 cm. Calculate the missing side.

777444111111

Video Solution

Step-by-Step Solution

We replace the data in the formula to find the perimeter:

25=4+7+11+x 25=4+7+11+x

25=22+x 25=22+x

2522=x 25-22=x

3=x 3=x

Answer

3 3 cm

Exercise #8

Given an isosceles trapezoid, calculate its perimeter

666101010121212AAABBBCCCDDD

Video Solution

Step-by-Step Solution

Since this is an isosceles trapezoid, and the two legs are equal, we can state that:

AB=CD=6 AB=CD=6

Now let's add all the sides together to find the perimeter

6+6+10+12= 6+6+10+12=

12+22=34 12+22=34

Answer

34

Exercise #9

If X=3

Calculate the perimeter of the trapezoid

XXX101010X+1X+1X+16+X6+X6+XAAABBBCCCDDD

Video Solution

Step-by-Step Solution

To calculate the perimeter, we add up all the sides:

10+x+(6+x)+(x+1) 10+x+(6+x)+(x+1)

Now, given that x equals 3, we substitute in the appropriate places:

10+3+(6+3)+(3+1)= 10+3+(6+3)+(3+1)=

10+3+9+4= 10+3+9+4=

13+13=26 13+13=26

Answer

26

Exercise #10

Calculate the perimeter of the trapezoid below:

6669.879.879.8714.5214.5214.524.14.14.1

Step-by-Step Solution

To solve this problem, we'll apply the straightforward approach of summing up the lengths of all four sides of the trapezoid to determine its perimeter:

  • Step 1: Identify the side lengths: the top base is 66, the bottom base is 14.5214.52, the left side is 4.14.1, and the right side is 9.879.87.
  • Step 2: Apply the perimeter formula for the trapezoid: P=a+b+c+d P = a + b + c + d , where a=6a = 6, b=14.52b = 14.52, c=4.1c = 4.1, and d=9.87d = 9.87.
  • Step 3: Add the side lengths: P=6+14.52+4.1+9.87 P = 6 + 14.52 + 4.1 + 9.87 .

Now, performing the calculation:

P=6+14.52+4.1+9.87=34.49 P = 6 + 14.52 + 4.1 + 9.87 = 34.49

Therefore, the perimeter of the trapezoid is 34.49 34.49 .

Answer

34.49

Exercise #11

Calculate the perimeter of the trapezoid below:

12.2812.2812.2866617.517.517.55.15.15.1

Step-by-Step Solution

To solve this problem, we'll use the perimeter formula for a trapezoid, which is straightforward since all side lengths are provided:

  • Step 1: Identify the side lengths:
    Top base (aa): 12.2812.28 units
    Bottom base (bb): 17.517.5 units
    Left non-parallel side (cc): 5.15.1 units
    Right non-parallel side (dd): 66 units
  • Step 2: Apply the formula for the perimeter, which states:
    P=a+b+c+d P = a + b + c + d
  • Step 3: Substitute the known values into the formula:
    P=12.28+17.5+5.1+6 P = 12.28 + 17.5 + 5.1 + 6
  • Step 4: Perform the addition:

Calculating the sum:

12.28+17.5=29.78 12.28 + 17.5 = 29.78

29.78+5.1=34.88 29.78 + 5.1 = 34.88

34.88+6=40.88 34.88 + 6 = 40.88

Hence, the perimeter of the trapezoid is 40.8840.88 units.

Answer

40.88

Exercise #12

Calculate X in the trapezoid below.

Perimeter = P

131313121212555xxxp=36

Step-by-Step Solution

To solve this problem, we'll utilize the formula for the perimeter of a trapezoid.

The formula for the perimeter is given by:

  • P=a+b+c+d P = a + b + c + d

From the problem, we know:

  • The perimeter P P is 36.
  • The side lengths are 13, 12, and 5, with the unknown side as x x .

Plug these into the formula:

36=13+12+5+x 36 = 13 + 12 + 5 + x

Combine the known side lengths:

36=30+x 36 = 30 + x

To isolate x x , subtract 30 from both sides:

x=3630 x = 36 - 30

Calculate the result:

x=6 x = 6

Therefore, the length of the missing side x x is 6.

Thus, the correct answer is choice 2, corresponding to x=6 x = 6 .

Answer

6

Exercise #13

Shown below is the isosceles trapezoid ABCD.

Given in cm:
BC = 7  

Height of the trapezoid (h) = 5

Perimeter of the trapezoid (P) = 34

Calculate the area of the trapezoid.

777h=5h=5h=5AAABBBCCCDDDEEE

Video Solution

Step-by-Step Solution

Since ABCD is a trapezoid, one can determine that:

AD=BC=7 AD=BC=7

Thus the formula to find the area will be

SABCD=(AB+DC)×h2 S_{ABCD}=\frac{(AB+DC)\times h}{2}

Since we are given the perimeter of the trapezoid, we can findAB+DC AB+DC

PABCD=7+AB+7+DC P_{ABCD}=7+AB+7+DC

34=14+AB+DC 34=14+AB+DC

3414=AB+DC 34-14=AB+DC

20=AB+DC 20=AB+DC

Now we will place the data we obtained into the formula in order to calculate the area of the trapezoid:

S=20×52=1002=50 S=\frac{20\times5}{2}=\frac{100}{2}=50

Answer

50

Exercise #14

ABCD is an isosceles trapezoid.

AB = 3

CD = 6

The area of the trapezoid is 9 cm².

What is the perimeter of the trapezoid?

333666AAABBBDDDCCCEEE

Video Solution

Step-by-Step Solution

We can find the height BE by calculating the trapezoidal area formula:

S=(AB+CD)2×h S=\frac{(AB+CD)}{2}\times h

We replace the known data: 9=(3+6)2×BE 9=\frac{(3+6)}{2}\times BE

We multiply by 2 to get rid of the fraction:

9×2=9×BE 9\times2=9\times BE

18=9BE 18=9BE

We divide the two sections by 9:

189=9BE9 \frac{18}{9}=\frac{9BE}{9}

2=BE 2=BE

If we draw the height from A to CD we get a rectangle and two congruent triangles. That is:

AF=BE=2 AF=BE=2

AB=FE=3 AB=FE=3

ED=CF=1.5 ED=CF=1.5

Now we can find one of the legs through the Pythagorean theorem.

We focus on triangle BED:

BE2+ED2=BD2 BE^2+ED^2=BD^2

We replace the known data:

22+1.52=BD2 2^2+1.5^2=BD^2

4+2.25=DB2 4+2.25=DB^2

6.25=DB2 6.25=DB^2

We extract the root:

6.25=DB \sqrt{6.25}=DB

2.5=DB 2.5=DB

Now that we have found DB, it can be argued that:

AC=BD=2.5 AC=BD=2.5

We calculate the perimeter of the trapezoid:6+3+2.5+2.5= 6+3+2.5+2.5=

9+5=14 9+5=14

Answer

14

Exercise #15

ABC is an isosceles triangle.

AD is the height of triangle ABC.

555333171717888AAABBBCCCDDDEEEFFFGGG

AF = 5

AB = 17
AG = 3

AD = 8

What is the perimeter of the trapezoid EFBC?

Video Solution

Step-by-Step Solution

To find the perimeter of the trapezoid, all its sides must be added:

We will focus on finding the bases.

To find GF we use the Pythagorean theorem: A2+B2=C2 A^2+B^2=C^2 in the triangle AFG

We replace

32+GF2=52 3^2+GF^2=5^2

We isolate GF and solve:

9+GF2=25 9+GF^2=25

GF2=259=16 GF^2=25-9=16

GF=4 GF=4

We perform the same process with the side DB of the triangle ABD:

82+DB2=172 8^2+DB^2=17^2

64+DB2=289 64+DB^2=289

DB2=28964=225 DB^2=289-64=225

DB=15 DB=15

We start by finding FB:

FB=ABAF=175=12 FB=AB-AF=17-5=12

Now we reveal EF and CB:

GF=GE=4 GF=GE=4

DB=DC=15 DB=DC=15

This is because in an isosceles triangle, the height divides the base into two equal parts so:

EF=GF×2=4×2=8 EF=GF\times2=4\times2=8

CB=DB×2=15×2=30 CB=DB\times2=15\times2=30

All that's left is to calculate:

30+8+12×2=30+8+24=62 30+8+12\times2=30+8+24=62

Answer

62