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Last updated at May 29, 2018 by Teachoo

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Supplementary Exercise Q5 Find the value of 𝜆 if the following vectors are co-planar (i) 𝑎 = 2 𝑖 − 𝑗 + 𝑘, 𝑏 = 𝑖 + 2 𝑗 − 3 𝑘, and 𝑐 = 3 𝑖 − 𝜆 𝑗 + 5 𝑘 Three vectors 𝑎, 𝑏, 𝑐 are coplanar if 𝒂 𝒃 𝒄 = 0 Given, 𝑎 = 2 𝑖 − 𝑗 + 𝑘 𝑏 = 𝑖 + 2 𝑗 − 3 𝑘 𝑐 = 3 𝑖 − λ 𝑗 + 5 𝑘 𝑎 𝑏 𝑐 = 2−1112−33−𝜆5 0 = 2 2×5−(−λ×−3) − (−1) 1×5−(3×−3) + 1 1×−λ−(3×2) 0 = 2 10−3λ + 5+9 + −λ−6 0 = 20 – 6λ + 14 – λ +– 6 0 = –7λ + 28 7λ = 28 λ = 287 𝝀 = 4 Therefore, 𝑎,𝑏, 𝑐 are coplanar if λ = 4 Supplementary Exercise Q5 Find the value of 𝜆 if the following vectors are co-planar (ii) 𝑎 = 2 𝑖 + 𝑗 + 𝑘, 𝑏 = 2 𝑖 − 𝜆 𝑗 + 𝑘, and 𝑐 = 5 𝑖 − 𝑗 − 3 𝑘 Three vectors 𝑎, 𝑏, 𝑐 are coplanar if 𝒂 𝒃 𝒄 = 0 Given, 𝑎 = 2 𝑖 + 𝑗 + 𝑘 𝑏 = 2 𝑖 − λ 𝑗 + 𝑘 𝑐 = 5 𝑖 + 𝑗 – 3 𝑘 𝑎 𝑏 𝑐 = 2112−𝜆151−3 0 = 2 −λ×−3−(1×1) − 1 2×−3−(5×1) + 1 2×1−(5×−λ) 0 = 2 3λ−1 − 1 −6−5 + 1 2+5λ 0 = 6λ – 2 + 11 + 2 + 5λ 0 = 11λ + 11 –11λ = 11 λ = 11−11 𝝀 = –1 Therefore, 𝑎,𝑏, 𝑐 are coplanar if λ = –1

Supplementary examples and questions from CBSE

Supplementary Example 1

Supplementary Example 2

Supplementary Example 3

Supplementary Example 4

Supplementary Example 5

Supplementary Example 6

Supplementary Exercise Q1

Supplementary Exercise Q2

Supplementary Exercise Q3

Supplementary Exercise Q4

Supplementary Exercise Q5 You are here

Supplementary Exercise Q6

Supplementary Exercise Q7

Supplementary Exercise Q8

Supplementary Exercise Q9

Supplementary Exercise Q10

About the Author

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.