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Example 13 - Find angle between vectors  a and b, magnitudes

Example 13 - Chapter 10 Class 12 Vector Algebra - Part 2

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Example 13 Find the angle between two vectors π‘Ž βƒ— and 𝑏 βƒ— with magnitudes 1 and 2 respectively and when π‘Ž βƒ— ⋅𝑏 βƒ— =1. "Given |" 𝒂 βƒ—"| = 1 , |" 𝒃 βƒ—"| = 2 , " "and " 𝒂 βƒ—". " 𝒃 βƒ—" = 1" We know that 𝒂 βƒ— . 𝒃 βƒ— = "|" 𝒂 βƒ—"|" "|" 𝒃 βƒ—"|" cos ΞΈ where ΞΈ is the angle between π‘Ž βƒ— and 𝑏 βƒ— Putting values in formula π‘Ž βƒ— . 𝑏 βƒ— = "|" π‘Ž βƒ—"|" "|" 𝑏 βƒ—"|" cos ΞΈ 1 = 1 Γ— 2 Γ— cos ΞΈ cos ΞΈ = 1/2 cos ΞΈ = cos 𝝅/πŸ‘ So, ΞΈ = 𝝅/πŸ‘ Thus angle b/w π‘Ž βƒ— and 𝑏 βƒ— is πœ‹/3 .

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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 12 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.