Question

Construct $\overline{\mathrm{AB}}$ of length $7.8\mathrm{cm}$. From this, cut off $\overline{\mathrm{AC}}$ of length $4.7\mathrm{cm}$. Measure $\overline{\mathrm{BC}}$.

Answer 1

Step 1: Constructing line segment $\overline{\mathrm{AB}}$

Draw a line $l$ and mark a point $A$ on it.

Since the length of $\overline{\mathrm{AB}}$ is $7.8\mathrm{cm}$, by adjusting the compass up to $7.8\mathrm{cm}$, while placing the pointer of compass at point $A$, draw an arc to cut the line $l$ at $B$.

Thus, $\overline{\mathrm{AB}}$ is the line segment of $7.8\mathrm{cm}$.

Step 2: Constructing line segment $\overline{\mathrm{AC}}$

Now, we need to cut $\overline{\mathrm{AC}}$ of length $4.7\mathrm{cm}$.

By adjusting the compass up to $4.7\mathrm{cm}$, while placing the pointer of compass on point $A$, draw an arc to cut the line $l$ at $C$.

So, $\overline{\mathrm{AC}}$ is the line segment of length $4.7\mathrm{cm}$.

Step 3: Measuring $\overline{\mathrm{BC}}$

Now, place the ruler in such a way that the $0$ mark of the ruler will match with point $C$.

measure the distance between the point $C$ and point $B$.

Thus, we get the length of the line segment $\overline{\mathrm{BC}}$ as $3.1\mathrm{cm}$.