The value of for which the angle between the vectors and is acute and the angle…

MATHEMATICS · Single correct · CBSE · Mathematics · Vector Algebra · Vector Algebra

Problem

The value of

x

for which the angle between the vectors

\mathbf{a} = -3\hat{i} + x\hat{j} + \hat{k}

and

\mathbf{b} = x\hat{i} + 2x\hat{j} + \hat{k}

is acute and the angle between

\mathbf{b}

and

X

-axis lies between

\pi/2

and

\pi

satisfy (1)

x > 0

(2)

x < 0

(3)

x > 1

only (4)

x < -1

only