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Example 18 - Chapter 10 Class 12 Vector Algebra (Term 2)
Last updated at May 6, 2021 by Teachoo
Transcript
Example 18 If ๐ โ is a unit vector and (๐ฅ โ โ ๐ โ) โ (๐ฅ โ + ๐ โ) = 8 , then find |๐ฅ โ| Given ๐ โ is a unit vector So, ๐ โ has a magnitude 1. โด |๐ โ | = 1. Given that (๐ โ โ ๐ โ) โ (๐ โ + ๐ โ) = 8 ๐ฅ โ . ๐ฅ โ + ๐ฅ โ . ๐ โ โ ๐ โ . ๐ โ โ ๐ โ . ๐ โ = 8 ๐ฅ โ . ๐ฅ โ + ๐ฅ โ . ๐ โ โ ๐ โ . ๐ โ โ ๐ โ . ๐ โ = 8 ๐ โ . ๐ โ โ ๐ โ . ๐ โ = 8 |๐ โ |2 โ |๐ โ |2 = 8 |๐ฅ โ |2 โ 12 = 8 (Using: ๐ฅ โ . ๐ โ = ๐ โ . ๐ฅ โ ) |๐ฅ โ |2 = 8 + 1 |๐ฅ โ |2 = 9 |๐ฅ โ | = ยฑ โ9 |๐ฅ โ | = ยฑ 3 Since magnitude is not negative, โด |๐ โ | = 3
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About the Author
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.