If is the angle between two vectors a and b , then a b 0 only 0 < < 2 0 2 0 < < 0

Correct Option is b (B) a b 0 | a | | b | 0 0 0 2

Vector Algebra — Class 12 Maths Solution

ncert misc SA NCERT,Page 459,Misc,Q.No 16

Question

If $\theta$ is the angle between two vectors $\vec a$ and $\vec b$, then $\vec a \cdot \vec b \ge 0$ only

• $0 < \theta < \cfrac{\pi }{2}$

• $0 \le \theta \le \cfrac{\pi }{2}$

• $0 < \theta < \pi$

• $0 \le \theta \le \pi$

Step-by-step Solution

{Correct Option is b}

(B) $\vec a \cdot \vec b \ge 0 \Rightarrow \left| {\vec a} \right|\left| {\vec b} \right|\cos \theta \ge 0 \Rightarrow \cos \theta \ge 0$

$\Rightarrow$ $0 \le \theta \le \cfrac{\pi }{2}$

NCERT & Exemplar solution for CBSE Class 12 Mathematics, Vector Algebra. Curated by Sachin Sharma. Free for all students.