How To Construct a Line Segment(With Steps & Examples)

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A line segment is a straight line with two endpoints. A line segment has a fixed length and can be measured using a ruler. Constructing a line segment is the basic construction in Geometry.

Let’s understand how to construct a line segment with steps and examples.

How to Construct a Line Segment of Given Length

Suppose we want to construct a line segment of length $4.3$ cm using ruler. We can use our ruler and mark two points $\text{A}$ and $\text{B}$ which are $4.3$ cm apart. Join $\text{A}$ and $\text{B}$ and get $\text{AB}$. While marking points $\text{A}$ and $\text{B}$, we should look straight down at the measuring device. Otherwise, we will get an incorrect value.

Steps to Construct a Line Segment of Given Length

These are the steps to construct a line segment of length $4.3$ cm using ruler.

Step 1: Draw a line $l$. Mark a point $\text{A}$ on a line $l$.

Step 2: Place the compass pointer on the zero mark of the ruler. Open it to place the pencil point up to the $4.3$ cm mark.

Step 3: Taking caution that the opening of the compasses has not changed, place the pointer on $\text{A}$ and swing an arc to cut $l$ at $\text{B}$.

Step 4: $overline{\text{AB}}$ is a line segment of a required length.

How to Construct a Copy of a Given Line Segment

After understanding how to construct a line segment, let’s understand how to construct a copy of a given line segment. Suppose you want to draw a line segment whose length is equal to that of a given line segment $\overline{\text{AB}}$ using a ruler and a compass.

Steps to Construct a Copy of a Given Line Segment

These are the steps to construct a copy of a given line segment.

Step 1: Given $\overline{\text{AB}}$ whose length is not known.

Step 2: Fix the compass pointer on $\text{A}$ and the pencil end on $\text{B}$. The opening of the instrument now gives the length of $\text{AB}$.

Step 3: Draw any line $l$. Choose a point $\text{C}$ on $l$. Without changing the compass’s setting, place the pointer on $\text{C}$.

Step 4: Swing an arc that cuts $l$ at a point $\text{D}$. Now $\text{CD}$ is a copy of $\text{AB}$.

Practice Problems

1. Construct a line segment of length
   • $2.8$ cm
   • $5.4$ cm
   • $7.2$ cm
2. Construct a copy of the above line segments.

FAQs

Conclusion

A line segment is a part of a line of fixed length. We can construct a line segment using a ruler and a compass and the same instruments are used to copy a given line segment.

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