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Ex 12.2, 8 - A floral design on a floor is made up of - Finding area of quadrilateral

Ex 12.2, 8 - Chapter 12 Class 9 Herons Formula - Part 2
Ex 12.2, 8 - Chapter 12 Class 9 Herons Formula - Part 3

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Ex 12.2, 8 A floral design on a floor is made up of 16 tiles which are triangular, the sides of the triangle being 9 cm, 28 cm and 35 cm (see the given figure). Find the cost of polishing the tiles at the rate of 50p per cm2. There are total 16 tiles , in shape of triangle Area of tiles = 16 Area of 1 triangle Area of triangle Area of triangle = (s(s a)(s b)(s c)) Here, s is the semi-perimeter, and a, b, c are the sides of the triangle Here, a = 9cm , b = 28cm, c =35cm s = ( + + )/2 Area of triangle = ( ( )( )( )) Putting a = 9, b = 28 , c = 35 & s = 36 = (36(36 9)(36 28)(36 35)) = (36" " (27) " " (8)" " (1)) = (36" " (9" " 3) " " (4" " 2)) = ((36)" " (9)" (4" ) " " (3)" (" 2)) = ((62)" " (32)" (22" ) " " (3)" (" 2)) = 62 32 22 (3 2) = 6 3 2 ((6) ) = 36 6 cm2 = 36 2.45 cm2 = 88.2 cm2 Area of tiles = 16 Area of 1 triangle ABC = (16 88.2) cm2 = 1411.2 cm2 Cost of polishing per cm2 area = 50 p Cost of polishing 1411.2 cm2 area = Rs (1411.2 1/2) = Rs 705.60 Therefore, it will cost 705.60 while polishing all the tiles.

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.