# Ex 11.4, 11 - Chapter 11 Class 7 Perimeter and Area

Last updated at Dec. 12, 2018 by Teachoo

Last updated at Dec. 12, 2018 by Teachoo

Transcript

Ex 11.4, 11 Find the area of the quadrilateral ABCD. Here, AC = 22 cm, BM = 3 cm, DN = 3 cm, and BM ⊥ AC, DN ⊥ AC Area of quadrilateral ABCD = Area of ∆ABC + Area of ∆ADC Area of ∆ABC Base = b = AC = 22 cm Height = BM = 3 cm Area of ∆ABC = 1/2 × b × h = 1/2 × AC × BM = 1/2 × 22 × 3 = 1/1 × 11 × 3 = 33 cm2 Area of ∆ABC Base = b = AC = 22 cm Height = BM = 3 cm Area of ∆ABC = 1/2 × b × h Area of ∆ADC Base = b = AC = 22 cm Height = ND = 3 cm Area of ∆ABC = 1/2 × b × h = 1/2 × AC × BM = 1/2 × 22 × 3 = 1/1 × 11 × 3 = 33 cm2 = 1/2 × AC × ND = 1/2 × 22 × 3 = 1/1 × 11 × 3 = 33 cm2 Therefore, Area of quadrilateral ABCD = Area of ∆ABC + Area of ∆ADC = 33 + 33 = 66 cm2 ∴ Area of quadrilateral is 66 cm2

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Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 10 years. He provides courses for Maths and Science at Teachoo.