Lines and Symmetry — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. A square has 2 pairs of parallel sides.
A square has 4 sides forming 2 pairs of parallel sides: top/bottom and left/right.
2. A trapezoid has 1 pair(s) of parallel sides.
A trapezoid (by definition) has exactly one pair of parallel sides.
3. A regular octagon has 8 lines of symmetry.
A regular octagon has 8 equal sides → 8 lines of symmetry.
4. The opposite sides of a rectangle are both parallel and equal.
In a rectangle, opposite sides are parallel (never meet) and equal in length.
5. A scalene triangle has 0 lines of symmetry.
A scalene triangle has all sides of different lengths, so no fold produces two matching halves — 0 lines of symmetry.
6. Perpendicular lines create four right angles at their intersection.
Two perpendicular lines intersecting create four 90° (right) angles.
7. The letter X has 2 lines of symmetry.
The capital letter X has a vertical and a horizontal line of symmetry — 2 total.
8. A parallelogram has 0 lines of symmetry.
A general parallelogram (not a rectangle or rhombus) has no lines of symmetry.
9. A line of symmetry is also called a line of reflection.
A line of symmetry acts as a mirror — folding along it reflects each half onto the other, hence also called a line of reflection.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
Square
→ 4 lines of symmetry
3 lines of symmetry
Equilateral triangle
→ 3 lines of symmetry
0 lines of symmetry
Rectangle
→ 2 lines of symmetry
4 lines of symmetry
Scalene triangle
→ 0 lines of symmetry
2 lines of symmetry
Square → 4 lines; Equilateral triangle → 3 lines; Rectangle → 2 lines; Scalene triangle → 0 lines.