Geometry
GradesGrade 4GeometryParallel & Perpendicular Lines

Parallel & Perpendicular Lines

📐 Geometry
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Parallel & Perpendicular Lines

Parallel lines never meet; perpendicular lines cross at a perfect right angle!

PARALLEL lines run in the same direction and are always the same distance apart — they NEVER intersect. PERPENDICULAR lines intersect at a RIGHT ANGLE (90°). These relationships are all around us in buildings, roads, and everyday objects.

Parallel lines (âˆĨ)

Never intersectAlways equidistant apartLike railroad tracks or opposite sides of a rectangleSymbol: AB âˆĨ CD

Perpendicular lines (âŠĨ)

Intersect at exactly 90°Form four right angles at the crossingLike the x-axis and y-axis, or + shaped roadsSymbol: AB âŠĨ CD

Two lines can be parallel, perpendicular, or simply intersecting (crossing at a non-right angle).

🏙ī¸Parallel and perpendicular in the city
Opposite sides of a city block → parallel streets
Main St. crossing Oak Ave. at a T intersection at 90° → perpendicular
A diagonal road crossing Main St. at 60° → simply intersecting (not perpendicular)

Identifying parallel and perpendicular in shapes:

1Look for ARROWS on sides of a shape — matching arrows mean parallel sides
2Look for the small SQUARE symbol in a corner — that marks a right angle (perpendicular sides)
3Rectangles: opposite sides parallel, adjacent sides perpendicular
4Parallelograms: opposite sides parallel, but sides NOT perpendicular (unless it is a rectangle)
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A rectangle has 2 pairs of parallel sides AND 4 pairs of perpendicular sides. It is a very special quadrilateral!

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Remember This!

Test for perpendicularity with a corner of a piece of paper — it is a perfect 90° angle. Slide it into the corner of the intersection and see if the sides line up!

✏ī¸ Try It!

Which shape has exactly ONE pair of parallel sides and NO perpendicular sides?

Take Quiz 📝 — 25 Questions