Q1
In a parallelogram, diagonals:
Abisect each other
Bare always equal in length
Cnever intersect
Dare perpendicular to each other
CBSEClass 9 (CBSE)MathematicsCh 8 · Topic 1
Properties of a Parallelogram
Learning the key properties that define a parallelogram.
Core concept
These properties can each be proven using congruent triangles formed by a parallelogram's diagonal, which divides it into two triangles that can be shown congruent using the ASA or SAS criteria, alongside properties of parallel lines and transversals. Understanding these properties thoroughly is essential, since many geometry problems require using one or more of these facts to prove other results or find unknown angles and lengths within a parallelogram-based figure.
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CBSE class 9 properties of a parallelogram
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• Parallelogram: opposite sides equal and parallel, opposite angles equal.
• Consecutive (adjacent) angles in a parallelogram are supplementary (sum to 180°).
• Diagonals of a parallelogram bisect each other (cross at their exact midpoints).
• These properties are proven using congruent triangles formed by a diagonal.