Calculate Parallelogram Area: Circle with Circumference 25.13 and Tangent Points

Tangent Parallelogram Area with Circle Properties

Below is a circle bounded by a parallelogram:

36

All meeting points are tangential to the circle.
The circumference is 25.13.

What is the area of the parallelogram?

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:11 Let's find the area of the parallelogram.
00:15 Lines starting from the same point are equal until they meet.
00:24 A side is equal to the sum of its parts.
00:34 Draw a diameter in the circle.
00:39 The radius is always at a right angle to the tangent where they meet.
00:44 We'll use the circle's circumference formula to find the radius.
00:49 Let's substitute the values and find the radius.
00:58 Round this radius. Now we know the radius and diameter!
01:05 To get the area, multiply the height, E H, by the side, A B.
01:11 Substitute the values and solve for the area.
01:14 And that's how we solve this problem.

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Below is a circle bounded by a parallelogram:

36

All meeting points are tangential to the circle.
The circumference is 25.13.

What is the area of the parallelogram?

2

Step-by-step solution

First, we add letters as reference points:

Let's observe points A and B.

We know that two tangent lines to a circle that start from the same point are parallel to each other.

Therefore:

AE=AF=3 AE=AF=3
BG=BF=6 BG=BF=6

And from here we can calculate:

AB=AF+FB=3+6=9 AB=AF+FB=3+6=9

Now we need the height of the parallelogram.

We know that F is tangent to the circle, so the diameter that comes out of point F will also be the height of the parallelogram.

It is also known that the diameter is equal to two radii.

Since the circumference is 25.13.

Circumference formula:2πR 2\pi R
We replace and solve:

2πR=25.13 2\pi R=25.13
πR=12.565 \pi R=12.565
R4 R\approx4

The height of the parallelogram is equal to two radii, that is, 8.

And from here you can calculate with a parallelogram area formula:

AlturaXLado AlturaXLado

9×872 9\times8\approx72

3

Final Answer

72 \approx72

Key Points to Remember

Essential concepts to master this topic
  • Tangent Property: Equal tangent segments from external point to circle
  • Technique: Use C=2πr C = 2\pi r to find radius from circumference 25.13
  • Check: Diameter equals height, area = base × height = 9 × 8 = 72 ✓

Common Mistakes

Avoid these frequent errors
  • Using circumference as diameter
    Don't use circumference 25.13 directly as the diameter = area of 226! The circumference must be divided by π to get diameter. Always use C = 2πr to find radius first, then diameter = 2r.

Practice Quiz

Test your knowledge with interactive questions

Calculate the area of the parallelogram according to the data in the diagram.

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FAQ

Everything you need to know about this question

Why are the tangent segments from each vertex equal?

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This is a fundamental tangent property! When two tangent lines are drawn from the same external point to a circle, the segments are always equal. So from point A: AE = AF = 3, and from point B: BG = BF = 6.

How do I find the parallelogram's height from the circle?

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The height equals the diameter of the inscribed circle! Since all sides are tangent to the circle, the distance between parallel sides equals the diameter = 2r.

Why is the base length 3 + 6 = 9?

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The base AB consists of two tangent segments: AF = 3 and FB = 6. Since these segments are adjacent on the same side, we add them: AB = AF + FB = 3 + 6 = 9.

How do I get radius 4 from circumference 25.13?

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Use the circumference formula: C=2πr C = 2\pi r
25.13=2πr 25.13 = 2\pi r
r=25.132π25.136.284 r = \frac{25.13}{2\pi} \approx \frac{25.13}{6.28} \approx 4

What if the parallelogram isn't drawn to scale?

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Always rely on the given measurements, not the visual appearance! Use the tangent lengths (3 and 6) and circumference (25.13) to calculate, regardless of how the diagram looks.

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