Why Area of a Trapezium : āĻŸā§ā§°āĻžāĻĒāĻŋāϜāĻŋāϝāĻŧāĻžāĻŽā§° āĻ•ā§āώ⧇āĻ¤ā§ā§°āĻĢāϞ āĻ•āĻŋāϝāĻŧ = 1/2(a + b)h






• A trapezium has only two parallel sides. : āĻŸā§ā§°āĻžāĻĒāĻŋāϜāĻŋāϝāĻŧāĻžāĻŽāϤ āĻ•ā§‡ā§ąāϞ āĻĻ⧁āϟāĻž āϏāĻŽāĻžāĻ¨ā§āϤ⧰āĻžāϞ āĻŦāĻžāĻšā§ āĻĨāĻžāϕ⧇āĨ¤


• Let the parallel sides be a and b, and h be the height. : āϧ⧰āĻž āĻšāĻ“āĻ• āϏāĻŽāĻžāĻ¨ā§āϤ⧰āĻžāϞ āĻŦāĻžāĻšā§ āĻĻ⧁āϟāĻž a āφ⧰⧁ b, āφ⧰⧁ h āĻšā§ˆāϛ⧇ āωāĻšā§āϚāϤāĻžāĨ¤


• Take two identical trapeziums. : āĻĻ⧁āϟāĻž āĻāϕ⧇ āϧ⧰āĻŖā§° āĻŸā§ā§°āĻžāĻĒāĻŋāϜāĻŋāϝāĻŧāĻžāĻŽ āĻ˛ā§‹ā§ąāĻž āĻšāϝāĻŧāĨ¤


Rotate one trapezium and join them together. : āĻāϟāĻž āĻŸā§ā§°āĻžāĻĒāĻŋāϜāĻŋāϝāĻŧāĻžāĻŽ āĻ˜ā§‚ā§°āĻžāχ āĻĻ⧁āϝāĻŧā§‹āϟāĻžāĻ• āĻāϕ⧇āϞāϗ⧇ āĻœā§‹ā§°āĻž āϞāĻžāϗ⧇āĨ¤


• They form a parallelogram. : āχāϝāĻŧāĻžā§° āĻĢāϞāϤ āĻāϟāĻž āϏāĻŽāĻžāĻ¨ā§āϤ⧰āϚāĻ¤ā§ā§°ā§āϭ⧁āϜ āĻ—āĻ āύ āĻšāϝāĻŧāĨ¤


Base of the parallelogram = a + b. : āϏāĻŽāĻžāĻ¨ā§āϤ⧰āϚāĻ¤ā§ā§°ā§āϭ⧁āϜ⧰ āĻ­āĻŋāĻ¤ā§āϤāĻŋ = a + bāĨ¤


Height of the parallelogram = h. : āϏāĻŽāĻžāĻ¨ā§āϤ⧰āϚāĻ¤ā§ā§°ā§āϭ⧁āϜ⧰ āωāĻšā§āϚāϤāĻž = hāĨ¤


Area of parallelogram = (a + b)h. : āϏāĻŽāĻžāĻ¨ā§āϤ⧰āϚāĻ¤ā§ā§°ā§āϭ⧁āϜ⧰ āĻ•ā§āώ⧇āĻ¤ā§ā§°āĻĢāϞ = (a + b)hāĨ¤


• Two trapeziums together make the parallelogram. : āĻĻ⧁āϟāĻž āĻŸā§ā§°āĻžāĻĒāĻŋāϜāĻŋāϝāĻŧāĻžāĻŽ āĻāϕ⧇āϞāϗ⧇ āĻŽāĻŋāϞāĻŋ āĻāϟāĻž āϏāĻŽāĻžāĻ¨ā§āϤ⧰āϚāĻ¤ā§ā§°ā§āϭ⧁āϜ āĻ—āĻ āύ āϕ⧰⧇āĨ¤



• So, Area of one trapezium = (a + b)h ÷ 2. : āϏ⧇āϝāĻŧ⧇ āĻāϟāĻž āĻŸā§ā§°āĻžāĻĒāĻŋāϜāĻŋāϝāĻŧāĻžāĻŽā§° āĻ•ā§āώ⧇āĻ¤ā§ā§°āĻĢāϞ = (a + b)h ÷ 2āĨ¤


• Area depends on the average of the parallel sides multiplied by height. : āĻ•ā§āώ⧇āĻ¤ā§ā§°āĻĢāϞ āϏāĻŽāĻžāĻ¨ā§āϤ⧰āĻžāϞ āĻŦāĻžāĻšā§ āĻĻ⧁āϟāĻžā§° āĻ—āĻĄāĻŧ āφ⧰⧁ āωāĻšā§āϚāϤāĻžā§° āϗ⧁āĻŖāĻĢāϞ⧰ āĻ“āĻĒā§°āϤ āύāĻŋā§°ā§āĻ­ā§° āϕ⧰⧇āĨ¤


Final Formula : Area of trapezium = ½ × (sum of parallel sides) × height


āĻšā§‚āĻĄāĻŧāĻžāĻ¨ā§āϤ āϏ⧂āĻ¤ā§ā§°: āĻŸā§ā§°āĻžāĻĒāĻŋāϜāĻŋāϝāĻŧāĻžāĻŽā§° āĻ•ā§āώ⧇āĻ¤ā§ā§°āĻĢāϞ = ½ × (āϏāĻŽāĻžāĻ¨ā§āϤ⧰āĻžāϞ āĻŦāĻžāĻšā§ āĻĻ⧁āϟāĻžā§° āϝ⧋āĻ—āĻĢāϞ) × āωāĻšā§āϚāϤāĻž


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Trapezium


1. Definition | āϏāĻ‚āĻœā§āĻžāĻž


Trapezium is a quadrilateral (four-sided figure) in which one pair of opposite sides are parallel and the other two sides are not parallel.


āĻŸā§ā§°ā§‡āĻĒāĻŋāϜāĻŋāϝāĻŧāĻžāĻŽ āĻšā§ˆāϛ⧇ āĻāϟāĻž āϚāĻžā§°āĻŋāĻŦāĻžāĻšā§āϝ⧁āĻ•ā§āϤ āφāĻ•āĻžā§° (Quadrilateral) āϝ’āϤ āĻāϟāĻž āĻŦāĻŋāĻĒā§°ā§€āϤ āĻŦāĻžāĻšā§ā§° āĻœā§‹ā§°āĻž āϏāĻŽāĻžāĻ¨ā§āϤ⧰āĻžāϞ (parallel) āĻĨāĻžāϕ⧇ āφ⧰⧁ āφāύ āĻĻ⧁āϟāĻž āĻŦāĻžāĻšā§ āϏāĻŽāĻžāĻ¨ā§āϤ⧰āĻžāϞ āύāĻšāϝāĻŧāĨ¤


2. Parts of a Trapezium | āĻŸā§ā§°ā§‡āĻĒāĻŋāϜāĻŋāϝāĻŧāĻžāĻŽā§° āĻ…āĻ‚āĻļāϏāĻŽā§‚āĻš

i. Bases (āϏāĻŽāĻžāĻ¨ā§āϤ⧰āĻžāϞ āĻŦāĻžāĻšā§) : The two parallel sides are called bases. : āĻĻ⧁āϟāĻž āϏāĻŽāĻžāĻ¨ā§āϤ⧰āĻžāϞ āĻŦāĻžāĻšā§āĻ• Base āĻŦ⧁āϞāĻŋ āĻ•ā§‹ā§ąāĻž āĻšāϝāĻŧāĨ¤


ii. Legs (āĻ…āϏāĻŽāĻžāĻ¨ā§āϤ⧰āĻžāϞ āĻŦāĻžāĻšā§) : The other two non-parallel sides are called legs. : āφāύ āĻĻ⧁āϟāĻž āĻ…āϏāĻŽāĻžāĻ¨ā§āϤ⧰āĻžāϞ āĻŦāĻžāĻšā§āĻ• Legs āĻŦ⧁āϞāĻŋ āĻ•ā§‹ā§ąāĻž āĻšāϝāĻŧāĨ¤


iii. Height (āωāĻšā§āϚāϤāĻž) : The perpendicular distance between the two bases is called height. : āĻĻ⧁āϟāĻž Base ā§° āĻŽāĻžāϜāϤ āĻĨāĻ•āĻž āϞāĻŽā§āĻŦ āĻĻā§‚ā§°āĻ¤ā§āĻŦāĻ• āωāĻšā§āϚāϤāĻž āĻŦ⧁āϞāĻŋ āĻ•ā§‹ā§ąāĻž āĻšāϝāĻŧāĨ¤


iv. Diagonals (āĻ•ā§°ā§āĻŖ) : The lines joining opposite vertices are called diagonals. : āĻŦāĻŋāĻĒā§°ā§€āϤ āĻļā§€ā§°ā§āώāĻŦāĻŋāĻ¨ā§āĻĻ⧁ āϏāĻ‚āϝ⧋āĻ— āϕ⧰āĻž ⧰⧇āĻ–āĻžāĻ• āĻ•ā§°ā§āĻŖ āĻŦ⧁āϞāĻŋ āĻ•ā§‹ā§ąāĻž āĻšāϝāĻŧāĨ¤


3. Types of Trapezium | āĻŸā§ā§°ā§‡āĻĒāĻŋāϜāĻŋāϝāĻŧāĻžāĻŽā§° āĻĒā§ā§°āĻ•āĻžā§°

i. Isosceles Trapezium (āϏāĻŽāĻĻā§āĻŦāĻŋāĻŦāĻžāĻšā§ āĻŸā§ā§°ā§‡āĻĒāĻŋāϜāĻŋāϝāĻŧāĻžāĻŽ) : In this trapezium, the two legs are equal in length and the base angles are also equal. : āĻāχ āĻŸā§ā§°ā§‡āĻĒāĻŋāϜāĻŋāϝāĻŧāĻžāĻŽāϤ āĻĻ⧁āϟāĻž āĻ…āϏāĻŽāĻžāĻ¨ā§āϤ⧰āĻžāϞ āĻŦāĻžāĻšā§ āϏāĻŽāĻžāύ āĻšāϝāĻŧ āφ⧰⧁ Base ā§° āϕ⧋āĻŖāϏāĻŽā§‚āĻšā§‹ āϏāĻŽāĻžāύ āĻšāϝāĻŧāĨ¤


ii. Right Trapezium (āϏāĻŽāϕ⧋āĻŖā§€ āĻŸā§ā§°ā§‡āĻĒāĻŋāϜāĻŋāϝāĻŧāĻžāĻŽ) : One of the legs is perpendicular to the base and it contains a right angle (90°). :  āĻāϟāĻž āĻŦāĻžāĻšā§ Base ā§° āϏ⧈āϤ⧇ āϞāĻŽā§āĻŦ āĻšāϝāĻŧ āφ⧰⧁ āχāϝāĻŧāĻžāϤ ⧝ā§Ļ° āϏāĻŽāϕ⧋āĻŖ āĻĨāĻžāϕ⧇āĨ¤


iii. Scalene Trapezium (āĻ…āϏāĻŽāĻŦāĻžāĻšā§ āĻŸā§ā§°ā§‡āĻĒāĻŋāϜāĻŋāϝāĻŧāĻžāĻŽ) : All sides and angles are different in this trapezium. : āĻāχ āĻŸā§ā§°ā§‡āĻĒāĻŋāϜāĻŋāϝāĻŧāĻžāĻŽāϤ āϏāĻ•āϞ⧋ āĻŦāĻžāĻšā§ āφ⧰⧁ āϕ⧋āĻŖ āĻ…āϏāĻŽāĻžāύ āĻšāϝāĻŧāĨ¤


4. Properties of Trapezium | āĻŸā§ā§°ā§‡āĻĒāĻŋāϜāĻŋāϝāĻŧāĻžāĻŽā§° āϗ⧁āĻŖāĻžāĻŦāϞ⧀

i. A trapezium has four sides and four angles. : āĻāϟāĻž āĻŸā§ā§°ā§‡āĻĒāĻŋāϜāĻŋāϝāĻŧāĻžāĻŽāϤ ā§ĒāϟāĻž āĻŦāĻžāĻšā§ āφ⧰⧁ ā§ĒāϟāĻž āϕ⧋āĻŖ āĻĨāĻžāϕ⧇āĨ¤


ii. One pair of opposite sides are parallel. : āĻāϟāĻž āĻŦāĻŋāĻĒā§°ā§€āϤ āĻŦāĻžāĻšā§ā§° āĻœā§‹ā§°āĻž āϏāĻŽāĻžāĻ¨ā§āϤ⧰āĻžāϞ āĻšāϝāĻŧāĨ¤


iii. The sum of all interior angles is 360°. : āĻ­āĻŋāϤ⧰⧰ āϏāĻ•āϞ⧋ āϕ⧋āĻŖā§° āϝ⧋āĻ—āĻĢāϞ ā§Šā§Ŧā§Ļ°āĨ¤


iv. The diagonals intersect each other inside the trapezium. : āĻ•ā§°ā§āĻŖ āĻĻ⧁āϟāĻž āĻŸā§ā§°ā§‡āĻĒāĻŋāϜāĻŋāϝāĻŧāĻžāĻŽā§° āĻ­āĻŋāϤ⧰āϤ āĻāϕ⧇ āĻ āĻžāχāϤ āϛ⧇āĻĻ āϕ⧰⧇āĨ¤


5. Area of a Trapezium | āĻŸā§ā§°ā§‡āĻĒāĻŋāϜāĻŋāϝāĻŧāĻžāĻŽā§° āĻ•ā§āώ⧇āĻ¤ā§ā§°āĻĢāϞ

Formula (āϏ⧂āĻ¤ā§ā§°): Area = ½ × (a + b) × h


Here a and b are the bases and h is the height. : āχāϝāĻŧāĻžāϤ a āφ⧰⧁ b āĻšā§ˆāϛ⧇ base āφ⧰⧁ h āĻšā§ˆāϛ⧇ āωāĻšā§āϚāϤāĻžāĨ¤


Example (āωāĻĻāĻžāĻšā§°āĻŖ): If the bases are 6 cm and 10 cm and the height is 5 cm, Area = ½ × (6 + 10) × 5 = 40 cm² : āϝāĻĻāĻŋ Base āĻĻ⧁āϟāĻž ā§Ŧ āϏ⧇āĻŽāĻŋ āφ⧰⧁ ā§§ā§Ļ āϏ⧇āĻŽāĻŋ āφ⧰⧁ āωāĻšā§āϚāϤāĻž ā§Ģ āϏ⧇āĻŽāĻŋ, āϤ⧇āĻ¨ā§āϤ⧇ āĻ•ā§āώ⧇āĻ¤ā§ā§°āĻĢāϞ = ā§Ēā§Ļ āĻŦā§°ā§āĻ— āϏ⧇āĻŽāĻŋāĨ¤


6. Perimeter of Trapezium | āĻŸā§ā§°ā§‡āĻĒāĻŋāϜāĻŋāϝāĻŧāĻžāĻŽā§° āĻĒā§°āĻŋāϏ⧀āĻŽāĻž

The perimeter of a trapezium is the sum of all four sides : āĻŸā§ā§°ā§‡āĻĒāĻŋāϜāĻŋāϝāĻŧāĻžāĻŽā§° āĻĒā§°āĻŋāϏ⧀āĻŽāĻž āĻšā§ˆāϛ⧇ āϚāĻžā§°āĻŋāϟāĻž āĻŦāĻžāĻšā§ā§° āĻŽā§āĻ  āϝ⧋āĻ—āĻĢāϞāĨ¤. Perimeter = a + b + c + d