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Linear Algebra Tool

Vector Projection Calculator

Calculate vector projections with comprehensive step-by-step solutions and geometric analysis. Our linear algebra calculator supports 2D and 3D vectors, scalar projections, dot products, and detailed mathematical explanations for advanced mathematics.

Last updated: December 15, 2024

2D and 3D vector support
Geometric interpretation
Scalar and vector projections

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Vector Projection Calculator
Calculate vector projections with detailed geometric analysis

Projection Formula:

projb(a) = ((a·b) / |b|²) × b

Projection Analysis

Vector Projection:

⟨3.0000, 0.0000⟩

Analysis Type:

Step-by-step solution

Scalar Projection:

3.0000

Projection Magnitude:

3.0000

Dot Product (a·b):

3.0000

Angle:

53.13°

Vector Magnitudes:

|a| = 5.0000
|b| = 1.0000
Unit vector b̂ = ⟨1.0000, 0.0000⟩

Solution Steps:

  1. 1. Given vectors: a = ⟨3.0000, 4.0000⟩, b = ⟨1.0000, 0.0000⟩
  2. 2. Calculate dot product: a·b = 3(1) + 4(0) = 3.0000
  3. 3. Calculate |b|²: 1² + 0² = 1.0000
  4. 4. Calculate |b|: √1.0000 = 1.0000
  5. 5. Scalar projection: comp_b(a) = (a·b)/|b| = 3.0000/1.0000 = 3.0000
  6. 6. Vector projection: proj_b(a) = ((a·b)/|b|²) × b = (3.0000/1.0000) × ⟨1.0000, 0.0000⟩
  7. 7. proj_b(a) = ⟨3.0000, 0.0000⟩
  8. 8. |proj_b(a)| = 3.0000

Analysis:

The projection of vector a onto vector b is ⟨3.0000, 0.0000⟩ with magnitude 3.0000. The scalar projection is 3.0000.

Vector Projection Tips:

  • Formula: projb(a) = ((a·b) / |b|²) × b
  • Scalar projection: compb(a) = (a·b) / |b|
  • Geometric meaning: "Shadow" of a onto b
  • Direction: Same as b if a·b > 0, opposite if a·b < 0

Quick Example Result

For projecting vector ⟨3, 4⟩ onto ⟨1, 0⟩:

proj = ⟨3.0000, 0.0000⟩

Scalar projection: 3.0000, Angle: 53.13°

How This Calculator Works

Our vector projection calculator applies fundamental linear algebra principles to compute the projection of one vector onto another. The calculator uses dot product operations and vector magnitude calculations to determine both scalar and vector projections, providing geometric insights and mathematical analysis for 2D and 3D vector spaces.

Vector Projection Algorithm

Step 1: Calculate Dot Product
a·b = a₁b₁ + a₂b₂ + a₃b₃
Step 2: Find Vector Magnitudes
|a| = √(a₁² + a₂² + a₃²), |b| = √(b₁² + b₂² + b₃²)
Step 3: Scalar Projection
comp_b(a) = (a·b) / |b|
Step 4: Vector Projection
proj_b(a) = ((a·b) / |b|²) × b

The vector projection algorithm systematically applies linear algebra operations to decompose vectors. The scalar projection comp_b(a) = (a·b)/|b| gives the signed length of the projection, while the vector projection proj_b(a) = ((a·b)/|b|²)b provides both magnitude and direction. The geometric interpretation represents the "shadow" of vector a when projected onto the line containing vector b.

Vector Projection Formulas:
Scalar: comp_b(a) = (a·b) / |b|
Vector: proj_b(a) = ((a·b) / |b|²) × b
Angle: θ = arccos((a·b) / (|a| × |b|))
Orthogonal: a_⊥ = a - proj_b(a)

Mathematical foundation for vector projection operations

Mathematical Foundation

Vector projection is fundamentally based on the dot product and the geometric relationship between vectors in Euclidean space. The projection of vector a onto vector b represents the component of a that lies in the direction of b. This operation is essential in linear algebra, as it allows us to decompose vectors into parallel and perpendicular components. The scalar projection gives us the signed magnitude, while the vector projection provides the actual vector result. The formula proj_b(a) = ((a·b)/|b|²)b ensures that the result lies along the direction of b with the correct magnitude.

  • Dot product measures the similarity and alignment between vectors
  • Projection decomposes vectors into parallel and perpendicular components
  • Scalar projection provides signed magnitude information
  • Vector projection gives both direction and magnitude of the component

Sources & References

  • Linear Algebra and Its Applications - David C. Lay, Steven R. Lay, Judi J. McDonaldComprehensive treatment of vector operations and projections
  • Wolfram MathWorld - Vector Projection ReferenceDetailed mathematical reference with geometric interpretations
  • Introduction to Linear Algebra - Gilbert StrangEducational treatment of vector spaces and linear transformations

Need help with other vector operations? Check out our dot product calculator and cross product calculator.

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Example Analysis

Force Component Problem
Finding the component of a force vector in a specific direction

Problem Setup:

  • Applied Force: F = ⟨50, 30⟩ N
  • Direction: d = ⟨3, 4⟩
  • Goal: Find force component along direction d
  • Application: Engineering stress analysis

Solution Process:

F·d = 50(3) + 30(4) = 270
|d| = √(3² + 4²) = 5
|d|² = 25
proj_d(F) = (270/25) × ⟨3, 4⟩
proj_d(F) = ⟨32.4, 43.2⟩ N

Result: Force component = ⟨32.4, 43.2⟩ N, Magnitude = 54.0 N

This engineering example demonstrates how vector projection helps analyze forces in structural design. The applied force F = ⟨50, 30⟩ N has a component of 54.0 N along the direction ⟨3, 4⟩. The calculation shows: F·d = 50×3 + 30×4 = 270, |d| = √(9+16) = 5, so the scalar projection is 270/5 = 54.0 N. The vector projection is (270/25) × ⟨3, 4⟩ = ⟨32.4, 43.2⟩ N. This represents the effective force component that acts along the specified direction, which is crucial for determining stress, strain, and structural integrity in engineering applications. The remaining component F - proj_d(F) = ⟨17.6, -13.2⟩ N acts perpendicular to direction d, contributing to shear forces in the structure.

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