Ex 9.1

Chapter 9 Class 7 Perimeter and Area
Serial order wise

Transcript

Ex 9.1, 3 Find the missing values: Base = 20 cm, Height = ?, Area = 246 cm2 Base = b = 20 cm Height = h Area of parallelogram = b × h 246 = 20 × h 𝟐𝟒𝟔/𝟐𝟎 = h 123/10 = h 12.3 = h h = 12.3 cm ∴ Height = 12.3 cm (b) Base = ?, Height = 15 cm, Area = 154.5 cm2 Base = b Height = h = 15 cm Area of parallelogram = b × h 154.5 = b × 15 154.5/15 = b b = (𝟏𝟓𝟒.𝟓)/𝟏𝟓 b = 1545/15 × 1/10 b = 𝟑𝟎𝟗/𝟑 × 𝟏/𝟏𝟎 b = 103 × 1/10 b = 10.3 cm ∴ Base = 10.3 cm (c) Base = ?, Height = 8.4 cm, Area = 48.72 cm2 Base = b Height = h = 8.4 cm Area of parallelogram = b × h 48.72 = b × 8.4 48.72/8.4 = b b = 48.72 × 𝟏/(𝟖.𝟒) b = 4872/100 × 10/84 b = 4872/10 × 1/84 b = 𝟒𝟖𝟕𝟐/𝟖𝟒 × 𝟏/𝟏𝟎 b = 1281/21 × 1/10 b = 406/7 × 1/10 b = 58 × 1/10 b = 5.8 cm ∴ Base = 5.8 cm (d) Base = 15.6 cm, Height = ?, Area = 16.38 cm2 Base = b = 15.6 cm Height = h Area of parallelogram = b × h 16.38 = 15.6 h 16.38/15.6 = h h = (𝟏𝟔.𝟑𝟖)/(𝟏𝟓.𝟔) h = 16.38 × 1/15.6 h = 𝟏𝟔𝟑𝟖/𝟏𝟎𝟎 × 𝟏𝟎/𝟏𝟓𝟔 h = 1638/10 × 1/156 h = 𝟏𝟔𝟑𝟖/𝟏𝟓𝟔 × 𝟏/𝟏𝟎 h = 819/78 × 1/10 h = 273/26 × 1/10 h = 𝟐𝟏/𝟐 × 𝟏/𝟏𝟎 h = 10.5 × 1/10 h = 1.05 ∴ Height = 1.05 cm

Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.