A quadrilateral is a closed figure with four sides and four angles. The sum of all interior angles in any quadrilateral is always 360°. This is the most fundamental property you must remember.
There are several types of quadrilaterals: parallelogram, rectangle, square, rhombus, trapezium, and kite. Each has unique properties that SSC CGL tests regularly.
All angles are 90°. Diagonals are equal and bisect each other
All sides equal, all angles 90°. Diagonals are equal, perpendicular, and bisect each other
All sides equal. Diagonals are perpendicular and bisect each other
One pair of opposite sides is parallel. Kite: Two pairs of adjacent sides are equal. One diagonal bisects the other at right angles
Parallelogram: Base × Height Rectangle: Length × Breadth Square: Side² Rhombus: (1/2) × d1 × d2 (where d1, d2 are diagonals) Trapezium: (1/2) × (sum of parallel sides) × height Kite: (1/2) × d1 × d2
finding area when diagonals are given, calculating perimeter from given conditions, property-based questions, and coordinate geometry problems involving quadrilaterals
For any quadrilateral with perpendicular diagonals, Area = (1/2) × d1 × d2. This works for rhombus, kite, and square. This single formula can solve multiple question types quickly.
Find Area Area = (1/2) × d1 × d2 Area = (1/2) × 16 × 12 = 96 cm²
Find Side Length Diagonals of rhombus bisect at right angles. Half diagonals: 8 cm and 6 cm Using Pythagoras: Side = √(8² + 6²) = √(64 + 36) = √100 = 10 cm
Find Perimeter Perimeter = 4 × side = 4 × 10 = 40 cm Another
When a quadrilateral's vertices are given in coordinate geometry, use the shoelace formula: Area = (1/2)|x1(y2-y4) + x2(y3-y1) + x3(y4-y2) + x4(y1-y3)|. This eliminates the need for multiple calculations.
Students often confuse rhombus and square properties. Remember: Square has all properties of rhombus PLUS all angles are 90°. Rhombus doesn't necessarily have 90° angles.
Also, many forget that in trapezium area formula, height is the perpendicular distance between parallel sides, not the slant side length.
8graded MCQs · easy to hard · full solution & trap analysis