CBSE · CLASS 9 · Science
PLANNED

Quadrilaterals

This official chapter is connected to Sanova AI. Detailed lesson content is currently being prepared.

Why This Matters

Quadrilaterals appear in buildings, screens, frames, fields and design.

Micro-Lessons

MICRO LESSON 1

What Is a Quadrilateral?

Picture it: Join four points to make a closed shape.

Simple: A quadrilateral has four sides, four vertices and four angles.

Example: Rectangle, square, kite.
Quick Check: How many diagonals?
MICRO LESSON 2

Angle Sum

Picture it: A quadrilateral can be split into two triangles.

Simple: Its interior angles sum to 360°.

Example: 90°+90°+90°+90°=360°.
Quick Check: Find fourth angle if others total 250°.
MICRO LESSON 3

Parallelogram

Picture it: Opposite sides run parallel.

Simple: A parallelogram has both pairs of opposite sides parallel.

Example: A slanted rectangle shape.
Quick Check: Are adjacent sides always equal?
MICRO LESSON 4

Parallelogram Properties

Picture it: Opposite sides and angles are equal.

Simple: Diagonals bisect each other.

Example: Each diagonal forms congruent triangles.
Quick Check: What do diagonals do?
MICRO LESSON 5

Rectangle

Picture it: A rectangle is a parallelogram with four right angles.

Simple: Its diagonals are equal and bisect each other.

Example: A book cover.
Quick Check: Are diagonals perpendicular always?
MICRO LESSON 6

Rhombus

Picture it: A rhombus has all sides equal.

Simple: Its diagonals bisect at right angles.

Example: Diamond shape.
Quick Check: Are all angles 90°?
MICRO LESSON 7

Square

Picture it: A square combines rectangle and rhombus properties.

Simple: All sides equal and all angles 90°.

Example: Floor tile.
Quick Check: What happens to diagonals?
MICRO LESSON 8

Midpoint Theorem

Picture it: A line joining midpoints of two sides of a triangle is parallel to third side and half its length.

Simple: This theorem links triangles and quadrilaterals.

Example: Midpoint segment mirrors the base.
Quick Check: If base is 10 cm, midpoint line?

Worked Examples

Three angles are 80°, 90°, 100°. Find fourth.

360°-270°=90°.

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