Type Of Quadrilaterals Notes For Class 9 Formulas Download PDF
A quadrilateral is a closed figure obtained by joining four point (with no three points collinear) in an order.
Every quadrilateral has :
(i) Four vertices
(ii) Four sides
(iii) Four angles
(iv) Two diagonals
Statement: The sum of the angles ofa quadrilateral is 360Â°
1. Trapezium : It is quadrilateral in which one pair of opposite sides are parallel.
2. Parallelogram : It is a quadrilateral in which both the pairs of opposite sides are parallel.
3. Rectangle : It is a quadrilateral whose each angle is 90Â°. ABCD is a rectangle.
(i) âˆ A+ âˆ B = 90Â° + 90Â° = 180Â° â‡” AD || BC
(ii) âˆ B+ âˆ C= 900 + 900 = 180Â° â‡” AB || DC
Rectangle ABCD is a parallelogram also.
4. Rhombus : It is a quadrilateral whose all the sides are equal.
5. Square : It is a quadrilateral whose all the sides are equal and each angle is 90Â°.
6. Kite : It is a quadrilateral in which two pairs of adjacent sides are equal.
â€¢ Square, rectangle and rhombus are all parallelograms.
â€¢Kite and trapezium are not parallelograms.
â€¢ A square is a rectangle.
â€¢ A square is a rhombus
â€¢ A parallelogram is a trapezium.
A parallelogram is a quadrilateral in which opposite sides are parallel. It is denoted by
1. A diagonal of a parallelogram divides it into two congruent triangles.
2. The opposite sides of a parallelogram are equal.
Theorem : If each pair of opposite sides of a quadrilateral is equal, then it is a parallelogram.
3. The opposite angles of a parallelogram are equal.
Theorem : If in a quadrilateral, each pair of opposite angles is equal, then it is a parallelogram.
4. The diagonals of a parallelogram bisect each other.
Theorem : If the diagonals of a quadrilateral bisect each other, then it is a parallelogram.
The line segment joining the mid-points of any two sides of a triangle is parallel to the third side
The line drawn through the mid-point of one side of a triangle, parallel to another side bisects the third side.
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