Lines and Symmetry — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. A line segment from point A to point B is written as AB.
Line segments are named using the two endpoint letters, written with a bar over them (AB̄), commonly written as AB.
2. A regular hexagon has 6 lines of symmetry.
A regular hexagon has 6 equal sides → 6 lines of symmetry (3 through opposite vertices, 3 through midpoints of opposite sides).
3. Two lines that meet at a right angle are called perpendicular.
Perpendicular lines (or segments) intersect at exactly 90°.
4. A ray starts at one point and goes on forever in one direction.
A ray has one endpoint (the starting point) and extends infinitely in one direction.
5. The letter H has 2 line(s) of symmetry.
The capital letter H has a vertical line of symmetry and a horizontal line of symmetry — 2 total.
6. An isosceles triangle has 1 line(s) of symmetry.
An isosceles triangle has exactly one line of symmetry — the perpendicular bisector of its base, through the apex.
7. Parallel lines are always the same distance apart.
The defining property of parallel lines is that the perpendicular distance between them is constant everywhere.
8. A rhombus has 2 lines of symmetry.
A rhombus has 2 lines of symmetry — both diagonals. (Unlike a square, its sides-to-corners lines are not lines of symmetry.)
9. The capital letter A has 1 line(s) of symmetry.
The capital letter A has one vertical line of symmetry down its center.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
Has two endpoints
→ Line segment
Ray
Goes forever in both directions
→ Line
Line segment
Has one endpoint
→ Ray
Parallel lines
Lines that never cross
→ Parallel lines
Line
Has two endpoints → Line segment; Goes forever in both directions → Line; Has one endpoint → Ray; Lines that never cross → Parallel lines.