Calculate the Missing Side in a Trapezoid with 25cm Perimeter

Perimeter Calculations with Unknown Sides

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

777444111111

❤️ Continue Your Math Journey!

We have hundreds of course questions with personalized recommendations + Account 100% premium

Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:06 Let's find the length of side B C.
00:09 Remember, the perimeter of a trapezoid is the total of all its sides added together.
00:21 Now, we'll put in the known values and solve, so we can find the length of B C.
00:44 Next, let's isolate B C to make it easier to find the answer.
00:54 And that's how we solve the problem! Great job!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

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

777444111111

2

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

3

Final Answer

3 3 cm

Key Points to Remember

Essential concepts to master this topic
  • Perimeter Formula: Add all four sides of the trapezoid together
  • Technique: Set up equation 25=4+7+11+x 25 = 4 + 7 + 11 + x
  • Check: Verify 4+7+11+3=25 4 + 7 + 11 + 3 = 25 cm ✓

Common Mistakes

Avoid these frequent errors
  • Adding only some of the given sides
    Don't add just two or three sides like 4 + 7 = 11, then solve 25 = 11 + x = wrong answer of 14! This ignores the third known side. Always add ALL known sides first: 4 + 7 + 11 = 22, then solve 25 = 22 + x.

Practice Quiz

Test your knowledge with interactive questions

Calculate the perimeter of the trapezoid according to the following data:

777101010777121212AAABBBCCCDDD

FAQ

Everything you need to know about this question

What is a perimeter and how do I find it?

+

Perimeter is the total distance around the outside of a shape. For any polygon, add up all the side lengths. In this trapezoid, we add all four sides together.

How do I set up the equation when one side is missing?

+

First, add up all the known sides: 4 + 7 + 11 = 22 cm. Then set up: 25=22+x 25 = 22 + x , where 25 is the total perimeter and x is the unknown side.

What if I get a negative number for the missing side?

+

Check your work! Side lengths must be positive. A negative result usually means you made an error in addition or subtraction. Re-add the known sides carefully.

Do I need to know what type of quadrilateral this is?

+

No! For perimeter problems, it doesn't matter if it's a trapezoid, rectangle, or any other quadrilateral. You simply add all the sides regardless of the shape.

How can I check if my answer makes sense?

+

Your missing side should be a reasonable positive number. Also, substitute back: if x = 3, then 4 + 7 + 11 + 3 should equal 25. Always verify!

🌟 Unlock Your Math Potential

Get unlimited access to all 18 Trapeze questions, detailed video solutions, and personalized progress tracking.

📹

Unlimited Video Solutions

Step-by-step explanations for every problem

📊

Progress Analytics

Track your mastery across all topics

🚫

Ad-Free Learning

Focus on math without distractions

No credit card required • Cancel anytime

More Questions

Click on any question to see the complete solution with step-by-step explanations