If for two unit vectors $\vec{a}$ and $\vec{b}$, $|\vec{a} + 2\vec{b}| = |2\vec{a} - \vec{b}|$, then find the angle between $\vec{a}$ and $\vec{b}$.

Year	Paper Code	Set	Position
CBSE 2026	Series 65-3	Set 1	Question 24
CBSE 2026	Series 65-3	Set 2	Question 22
CBSE 2026	Series 65-3	Set 3	Question 25

• Step 1: Stating the fundamental formula / law statement (+1 Mark)
• Step 2: Intermediate mathematical substitution or proof steps (+1 Mark)
• Step 3: Correct final value or conclusion with mandatory SI units (+1 Mark)