Ex 11.2

Chapter 11 Class 7 Perimeter and Area
Serial order wise

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### Transcript

Ex 11.2, 7 ΔABC is right angled at A (Fig 11.25). AD is perpendicular to BC. If AB = 5 cm, BC = 13 cm and AC = 12 cm, Find the area of Δ ABC. Also find the length of AD. We need to find area ∆ABC, As AB ⊥ AC Taking AB as height & AC as base Here, Base = AC = 12 cm Height = AB = 5 cm Area of ∆ABC = 1/2 × Base × Height = 1/2 × 12 × 5 = 6 × 5 = 30 cm2 Now, we have to find length of AD height corresponding to base BC So, finding Area using AD as height and BC as base Base = BC = 13 cm Height = AD = ? Area of ∆ABC = 1/2 × Base × Height 30 = 1/2 × BC × AD 30 = 1/2 × 13 × AD 30 = 13/2 × AD 30 × 2/13 = AD 60/13 = AD AD = 60/13 cm ∴ Area of ∆ABC is 30 cm2 and Length of AD is 𝟔𝟎/𝟏𝟑 cm

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#### Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.