✓ 1 MARKS
MCQ
🔥 APPEARED IN 3 BOARD SETS
If $(\vec{a} + \vec{b}) \cdot (\vec{a} - \vec{b}) = 198$ and $|\vec{a}| = 10\,|\vec{b}|$, then :
A
$|\vec{a}| = \sqrt{2}$
B
$|\vec{b}| = \sqrt{2}$
C
$|\vec{b}| = 10\sqrt{2}$
D
$|\vec{a}| = \frac{10}{\sqrt{2}}$
01 // VERIFIED BOARD OCCURRENCES
| Year | Paper Code | Set | Position |
|---|---|---|---|
| CBSE 2026 | Series 65-3 | Set 1 | Question 15 |
| CBSE 2026 | Series 65-3 | Set 2 | Question 8 |
| CBSE 2026 | Series 65-3 | Set 3 | Question 1 |
02 // OFFICIAL CBSE MARKING SCHEME BREAKDOWN
- 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)