Welcome to Quadrilaterals Mastery!
Discover the fascinating properties of parallelograms, rectangles, rhombuses, and more! Choose a lesson below to begin your geometric journey!
Key Concepts & Theorems
Parallelogram Definition
A parallelogram is a quadrilateral with both pairs of opposite sides parallel.
- Opposite sides are parallel
- Opposite sides are equal
- Opposite angles are equal
- Diagonals bisect each other
Diagonal Theorem
In a parallelogram, the diagonals bisect each other.
Using ASA congruence rule, we can prove that triangles formed by diagonals are congruent, making the diagonals bisect each other.
Opposite Sides Property
In a parallelogram, opposite sides are both parallel and equal in length.
AB ∥ DC and AB = DC
AD ∥ BC and AD = BC
Opposite Angles Property
In a parallelogram, opposite angles are equal.
∠A = ∠C and ∠B = ∠D
Special Quadrilaterals
Special types of parallelograms with additional properties.
- Rectangle: All angles are 90°
- Rhombus: All sides are equal
- Square: All sides equal + all angles 90°
Area Formula
The area of a parallelogram can be calculated using base and height.
Area = base × height
A = b × h