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  1. Chapter 10 Class 12 Vector Algebra
  2. Serial order wise

Transcript

Misc 3 A girl walks 4 km towards west, then she walks 3 km in a direction 30ยฐ east of north and stops. Determine the girlโ€™s displacement from her initial point of departure. Let initial point of departure be O(0, 0) & OA = 4km AB = 3km โˆ  XAB = 30ยฐ Here, Displacement will be vector (๐‘‚๐ต) โƒ— So, we need to find coordinates of B Now, โˆ  BAO = 90ยฐ โ€“ โˆ  XAB = 90ยฐ โ€“ 30ยฐ = 60ยฐ Let us draw BD โŠฅ OA In right triangle ADB sin 60ยฐ = ๐ต๐ท/๐ด๐ต โˆš3/2 = ๐ต๐ท/3 (3โˆš3)/2 = BD BD = (๐Ÿ‘โˆš๐Ÿ‘)/๐Ÿ In right triangle ADB cos 60ยฐ = ๐ด๐ท/๐ด๐ต 1/2 = ๐ด๐ท/3 3/2 = AD AD = ๐Ÿ‘/๐Ÿ Now, OD = OA โ€“ AD OD = 4 โ€“ ๐Ÿ‘/๐Ÿ = (๐Ÿ’(๐Ÿ) โˆ’ ๐Ÿ‘)/๐Ÿ = ๐Ÿ“/๐Ÿ So, x-coordinate of point B = โˆ’OD = (โˆ’๐Ÿ“)/๐Ÿ y-coordinate of point B = BD = (๐Ÿ‘โˆš๐Ÿ‘)/๐Ÿ Thus, coordinates of point B = ((โˆ’๐Ÿ“)/๐Ÿ, (๐Ÿ‘โˆš๐Ÿ‘)/๐Ÿ) So, Displacement = (โˆ’๐Ÿ“)/๐Ÿ ๐’Š ฬ‚ + (๐Ÿ‘โˆš๐Ÿ‘)/๐Ÿ ๐’‹ ฬ‚

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.