Consider the set of eight vectors V={aˆi+bˆj+cˆka,b,c∈{−1,1}}. Three non-coplanar vectors can be chosen from V in 2p ways, then p is
A
4
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
5
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
C
6
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
8
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution
The correct option is B5 Let (1,1,1),(−1,1,1),(1,−1,1),(−1,−1,1) be vectors →a,→b,→c,→d, rest of the vectors are −→a,−→b,−→c,−→d and let us find the number of ways of selecting co-planar vectors.
Observe that out of any three coplanar vectors two will be collinear (anti parallel). Number of ways of selecting the anti-parallel pair =4 Number of ways of selecting the third vector =6 Total =24 Number of non-coplanar selections =8C3−24=32=25,p=5 ∴p=5