38. A protractor has _____ line/lines of symmetry.
Answer: one.
Step-by-step explanation (very simple)
- Know the shape: A common school protractor is a semicircle (half of a circle).
It has a straight edge (the bottom) and a curved edge (the top) marked from
(0^circ) to (180^circ).
- What is a line of symmetry?
It is a line where, if you fold the shape along that line, both halves match exactly.
- Try a vertical line through the center:
Draw an imaginary line from the middle of the straight edge, going straight up through the center of the curve.
This line is perpendicular to the bottom edge.
If you fold the protractor along this line, the left half fits exactly over the right half.
So this is a line of symmetry.
- Try a horizontal line along the straight edge:
If you fold along the bottom straight edge, the curved part would try to match the straight part.
They do not match.
So this is not a line of symmetry.
- Any other slanted line?
Folding along any slanted line will not make the two halves match.
So those are not lines of symmetry.
- Conclusion:
A semicircular protractor has only one line of symmetry — the vertical line through its center (the perpendicular bisector of the diameter).
In short: Only the vertical line through the center makes both halves of the protractor match. Hence, one line of symmetry.