A parallel line with set squares
Draw AB = 5 cm and a point P above it. Draw a line through P parallel to AB with set squares.
Draw AB = 8 cm and a point P above it. Draw a line through P parallel to AB with set squares.
Draw AB = 7 cm and a point P above it. Draw a line through P parallel to AB with set squares.
Draw AB = 6 cm and a point P above it. Draw a line through P parallel to AB with set squares.
1. Draw AB = 5 cm, and mark a point P above it.
2. Put one edge of a set square exactly on AB, and hold a ruler firmly against its longest side.
3. Hold the ruler still and slide the set square along it, until the same edge reaches P.
4. Draw a line along that edge, through P. Call it ST: ST ∥ AB.
5. Take the set square away: ST is parallel to AB.
1. Draw AB = 8 cm, and mark a point P above it.
2. Put one edge of a set square exactly on AB, and hold a ruler firmly against its longest side.
3. Hold the ruler still and slide the set square along it, until the same edge reaches P.
4. Draw a line along that edge, through P. Call it ST: ST ∥ AB.
5. Take the set square away: ST is parallel to AB.
1. Draw AB = 7 cm, and mark a point P above it.
2. Put one edge of a set square exactly on AB, and hold a ruler firmly against its longest side.
3. Hold the ruler still and slide the set square along it, until the same edge reaches P.
4. Draw a line along that edge, through P. Call it ST: ST ∥ AB.
5. Take the set square away: ST is parallel to AB.
1. Draw AB = 6 cm, and mark a point P above it.
2. Put one edge of a set square exactly on AB, and hold a ruler firmly against its longest side.
3. Hold the ruler still and slide the set square along it, until the same edge reaches P.
4. Draw a line along that edge, through P. Call it ST: ST ∥ AB.
5. Take the set square away: ST is parallel to AB.
Why it works
Held against the ruler, the set square can only slide along it: it never turns. So its edge keeps the same direction it had on AB, and a line drawn along it in its new place makes the same angle with the ruler as AB does. Lines that make equal (corresponding) angles with a line across them are parallel.