JEE Main Maths · Vector Algebra PYQ
JEE Main Vector Algebra PYQ (2002–2026)
Vector Algebra is a P1 chapter — ~5% JEE Main weightage with 1–2 questions per session. It's the foundation for 3D Geometry and the physics chapters that use vectors (Mechanics, EMI). Mastery here unlocks both chapters at once.
Vector Algebra PYQs from 2002 to 2026, tagged by sub-topic (dot product, cross product, triple products, projections). Every KaTeX solution shows the vector decomposition and applies the appropriate formula.
Vector Algebra at a Glance
Try 5 Real Vector Algebra PYQs
5 real JEE Main questions on Vector Algebra, straight from past papers. Try them, then check the answer.
- Q1JEE Main 2026 (Online) 24th January Morning Shift
Let the lines $\mathrm{L}_1: \vec{r}$${}=\hat{\mathrm{i}}+2 \hat{\mathrm{j}}+3 \hat{\mathrm{k}}+\lambda(2 \hat{\mathrm{i}}+3 \hat{\mathrm{j}}+4 \hat{\mathrm{k}}), \lambda \in \mathbb{R}$ and $\mathrm{L}_2: \vec{r}$${}=(4 \hat{\mathrm{i}}+\hat{\mathrm{j}})+\mu(5 \hat{\mathrm{i}}+2 \hat{\mathrm{j}}+\hat{\mathrm{k}}), \mu \in \mathbb{R}$, intersect at the point R . Let P and Q be the points lying on lines $L_1$ and $L_2$, respectively, such that $|\overrightarrow{\mathrm{PR}}|$${}=\sqrt{29}$ and $|\overrightarrow{\mathrm{PQ}}|$${}=\sqrt{\frac{47}{3}}$. If the point P lies in the first octant, then $27(\mathrm{QR})^2$ is equal to
360
348
320
340
- Q2JEE Main 2025 (Online) 24th January Morning Shift
Let $\vec{a}$${}=\hat{i}+2 \hat{j}+3 \hat{k}, \vec{b}$${}=3 \hat{i}+\hat{j}-\hat{k}$ and $\vec{c}$ be three vectors such that $\vec{c}$ is coplanar with $\vec{a}$ and $\vec{b}$. If the vector $\vec{C}$ is perpendicular to $\vec{b}$ and $\vec{a} \cdot \vec{c}$${}=5$, then $|\vec{c}|$ is equal to
- $\sqrt{\frac{11}{6}}$
- $\frac{1}{3 \sqrt{2}}$
- 18
- 16
- Q3JEE Main 2024 (Online) 4th April Morning Shift
Let ABC be a triangle of area $15 \sqrt{2}$ and the vectors $\overrightarrow{\mathrm{AB}}$${}=\hat{i}+2 \hat{j}-7 \hat{k}, \overrightarrow{\mathrm{BC}}$${}=\mathrm{a} \hat{i}+\mathrm{b} \hat{j}+\mathrm{c} \hat{k}$ and $\overrightarrow{\mathrm{AC}}$${}=6 \hat{i}+\mathrm{d} \hat{j}-2 \hat{k}, \mathrm{~d}>0$. Then the square of the length of the largest side of the triangle ABC is _________.
- Q4JEE Main 2023 (Online) 6th April Morning Shift
Let the position vectors of the points A, B, C and D be $5 \hat{i}+5 \hat{j}+2 \lambda \hat{k}, \hat{i}+2 \hat{j}+3 \hat{k},-2 \hat{i}+\lambda \hat{j}+4 \hat{k}$ and $-\hat{i}+5 \hat{j}+6 \hat{k}$. Let the set $S$${}=\{\lambda \in \mathbb{R}$ : the points A, B, C and D are coplanar $\}$.
Then $\sum\limits_{\lambda \in S}(\lambda+2)^{2}$ is equal to :- $\frac{37}{2}$
- 25
- 13
- 41
- Q5JEE Main 2022 (Online) 25th June Evening Shift
Let $\overrightarrow b $${}= \widehat i + \widehat j + \lambda \widehat k$, $\lambda$ $\in$ R. If $\overrightarrow a $ is a vector such that $\overrightarrow a \times \overrightarrow b $${}= 13\widehat i - \widehat j - 4\widehat k$ and $\overrightarrow a \,.\,\overrightarrow b + 21 $${}= 0$, then $\left( {\overrightarrow b - \overrightarrow a } \right).\,\left( {\widehat k - \widehat j} \right) + \left( {\overrightarrow b + \overrightarrow a } \right).\,\left( {\widehat i - \widehat k} \right)$ is equal to _____________.
Practise the full Vector Algebra set
Every past-paper question of this chapter, with solutions, timing and your accuracy tracked.
Key Sub-Topics & What's Tested
Vector Basics
Position vector, unit vector, collinear vectors, coplanar vectors, vector addition (parallelogram/triangle law).
Dot Product (Scalar Product)
a·b = |a||b|cos θ, properties (commutative, distributive), a·a = |a|², perpendicular vectors a·b = 0.
Cross Product (Vector Product)
a × b = |a||b|sin θ n̂, anti-commutative, area of parallelogram = |a × b|, area of triangle = ½|a × b|.
Projection of Vector
Projection of a on b = (a·b)/|b|, vector projection, decomposition into parallel and perpendicular components.
Scalar Triple Product
[a b c] = a · (b × c), volume of parallelepiped, coplanarity condition [a b c] = 0, determinant form.
Vector Triple Product
a × (b × c) = (a·c)b - (a·b)c, BAC-CAB rule, applications in deriving identities.
Angles Between Vectors
cos θ = (a·b)/(|a||b|), sin θ = |a × b|/(|a||b|), using Cartesian components.
Coplanarity & Collinearity
Three vectors coplanar iff [a b c] = 0. Three points collinear iff vectors between them are parallel.
Question Type Distribution
| Question Type | Share (approx) | Example Pattern |
|---|---|---|
| Dot Product Application | 20% | Find angle between vectors a = 2i + 3j - k and b = i - j + 2k. |
| Cross Product / Area | 20% | Find area of triangle with vertices A(1,2,3), B(2,3,4), C(3,4,5). |
| Scalar Triple / Volume | 20% | Find volume of parallelepiped formed by vectors a, b, c given as 3-component vectors. |
| Projection Problems | 15% | Find projection of vector a = 3i + 4j onto b = i + j. |
| Coplanarity Check | 15% | Determine if vectors (1,0,1), (2,1,3), (3,1,4) are coplanar. |
| Vector Triple / Identity | 10% | Simplify a × (b × c) + b × (c × a) + c × (a × b). |
How to Solve Vector Algebra PYQs
- 1Dot product computes angles and projections. a·b = 0 → perpendicular. a·b > 0 → acute angle. a·b < 0 → obtuse. Basic but crucial.
- 2Cross product for area and perpendicular direction. |a × b| = area of parallelogram. a × b is perpendicular to both a and b. Never forget the perpendicular property.
- 3Scalar triple product = volume. [a b c] > 0 → right-handed system. [a b c] = 0 → coplanar vectors.
- 4Use Cartesian components for computation. Express vectors as (x, y, z) triples. Then compute dot/cross products via formulas in terms of components.
- 5BAC-CAB rule for vector triple product. a × (b × c) = b(a·c) - c(a·b) — memorise this one formula.
Common Mistakes That Cost Marks
- Wrong direction in cross product. a × b follows right-hand rule. a × b ≠ b × a; in fact, a × b = -b × a. Sign matters.
- Confusing dot and cross products in formulas. Dot product gives scalar. Cross product gives vector. Mixing these breaks dimensional analysis.
- Calling |a × b| the area of triangle. |a × b| is area of PARALLELOGRAM formed by a and b. Triangle area = half of that.
- Using |a| · |b| as projection. Projection of a on b = (a·b)/|b|. The scalar product is divided by the magnitude of b, not multiplied.
- Computing scalar triple as dot of triples. [a b c] = a · (b × c). NOT (a · b) · c — that doesn't make sense dimensionally.
Related JEE Main Practice
Frequently asked questions
How many Vectors PYQs should I solve?
Target 50–70 PYQs across 2010–2026. Given the chapter's cross-use in 3D Geometry and Physics, consistent practice has compound value.
Are Vectors questions computation-heavy or conceptual?
Both. ~60% computation (dot/cross products, triple products). ~40% conceptual (coplanarity, projection, geometric interpretation). Balance both types in practice.
Do I need to know vector identities by heart?
Core ones: BAC-CAB, scalar triple as determinant, a × (b × c) ≠ (a × b) × c (non-associative). These appear in derivation-type PYQs.
What's the most-tested Vectors PYQ pattern?
Coplanarity of three vectors via scalar triple product = 0. Appears in 3–4 PYQs per 10-year window. Master the determinant setup.
Do I need to know projection vs rejection separately?
Projection of a on b = (a·b/|b|²) b (vector). Rejection = a - projection. Most PYQs ask for projection (vector) or projection component (scalar). Know both terminologies.
How does Vectors connect with 3D Geometry?
3D Geometry uses vectors throughout — line equations, plane equations, shortest distance, angle between lines. Strong Vectors fluency directly helps 3D PYQs.
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