Rhombus diagonals are perpendicular bisectors
All sides equal; diagonals bisect each other at right angles and bisect the vertex angles.
Key formulas


Properties pack
A rhombus is a parallelogram with equal sides. Diagonals are perpendicular and bisect each other.
Area shortcut
Area = half product of diagonals. Diagonals 6 and 8 → area 24.
Side from diagonals
Half-diagonals 3 and 4 → side 5 by Pythagoras.
Worked example
Worked example
Problem. A rhombus has diagonals 6 cm and 8 cm. Find its side length and area.
Solution. Half-diagonals 3 and 4 form a right triangle: side = 5 cm. Area = (d₁d₂)/2 = 24 cm².
Square special case
A square is a rhombus with equal diagonals.
Review quiz
Diagonals 10 and 24. Rhombus side is:
Practice questions
- Diagonals 10 and 24. Find the side and the area.
- Why do the diagonals bisect the angles of a rhombus?
Study notes
Are diagonals equal?
Only if the rhombus is a square.
More in Plane Geometry
- Circle tangents: the radius is perpendicular
- Right-triangle lengths: Pythagoras and altitude
- Similar triangles: matching sides in proportion
- Chord theorem: perpendicular from the centre
- Isosceles triangles and equal base angles
- Alternate segment theorem with a short proof
- Converse of Pythagoras: proving a right angle
- Heron’s formula when height is hidden