MHT CET 2017 Math Solved Paper

(c) We have, vector r with dc’s l, m, n is equally inclined to the coordinate axes.
So, l = m = n ...(i)
As, l2+m2+n2=1
∴ l2+l2+l2=1 [ from eq. {i} ]
⇒3l2=1
⇒ l=±

1

√3

Therefore, l = m = n = ±

1

√3

∴ vector r = |r| (±

1

√3

∧

i

±

1

√3

∧

j

±

1

√3

∧

k

)
Hence, total number of required vectors = 23 = 8