Below is a circle bounded by a parallelogram:
All meeting points are tangential to the circle.
The circumference is 25.13.
What is the area of the parallelogram?
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Below is a circle bounded by a parallelogram:
All meeting points are tangential to the circle.
The circumference is 25.13.
What is the area of the parallelogram?
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:
And from here we can calculate:
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:
We replace and solve:
The height of the parallelogram is equal to two radii, that is, 8.
And from here you can calculate with a parallelogram area formula:
Calculate the area of the parallelogram according to the data in the diagram.
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.
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.
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.
Use the circumference formula:
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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