Supplementary Exercise Q10

Transcript

Supplementary Exercise Q10 If the vectors 𝐴 ⃗ = a𝑖 ̂ + 𝑗 ̂ + 𝑘 ̂, 𝐵 ⃗ = 𝑖 ̂ + b𝑗 ̂ + 𝑘 ̂ and 𝐶 ⃗ = 𝑖 ̂ + 𝑗 ̂ + c𝑘 ̂ are coplanar, then 1/(1−𝑎) + 1/(1−𝑏) + 1/(1−𝑐) = 1, where a, b, c ≠ 1 Since Vectors 𝐴 ⃗, 𝐵 ⃗, 𝐶 ⃗ are coplanar , ∴ [𝐴 ⃗" " 𝐵 ⃗" " 𝐶 ⃗ ] = 0 [𝐴 ⃗" " 𝐵 ⃗" " 𝐶 ⃗ ] = |■8(𝑎&1&1@1&𝑏&1@1&1&𝑐)| 0 = a[(𝑏×𝑐)−(1×1) ] − 1[(1×𝑐)−(1×1)] + 1[(1×1)−(1×𝑏) ] 0 = a [𝑏𝑐−1]−[𝑐−1]+1[1−𝑏] 0 = abc – a – c + 1 + 1 – b = 0