Find the least positive integral value of for which the angle between vectors and is…

MATHEMATICS · Subjective · AP · AP Precalculus · Functions with Parameters, Vectors, and Matrices · Functions with Parameters, Vectors, and Matrices

Problem

Find the least positive integral value of

x

for which the angle between vectors

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

and

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

is acute.