If the volume of a parallelepiped, whose coterminus edges are given by the vectors a⃗ = î + ĵ + nk̂, b⃗ = 2î + 4ĵ – nk̂ and c⃗ = î + nĵ + 3k̂(n ≥ 0), is 158 cu.units. then:
If the volume of a parallelepiped, whose coterminus edges are given by the vectors a⃗ = î + ĵ + nk̂, b⃗ = 2î + 4ĵ – nk̂ and c⃗ = î + nĵ + 3k̂(n ≥ 0), is 158 cu.units. then:
Option 1 -
A
Option 2 -
B
Option 3 -
C
Option 4 -
D
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1 Answer
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Correct Option - 3
Detailed Solution:Volume of parallelepiped v = | [a? b? c? ]|
v = | 1 n |
| 2 4 -n| = ±158
| 1 n 3 |
1 (12+n²) - 1 (6+n) + n (2n-4) = ±158
3n²-5n+152=0 or 3n²-5n+164=0
D<0 (no real roots)
n=8, -19/3 ⇒ n=8
then b? ⋅c? = 2+4n-3n=10
a? ⋅c? = 1+n+3n=33
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