外積計算機（A × B）
✓A × B
詳細ガイド 近日公開
Cross Product 計算機の包括的な教育ガイドを準備中です。ステップバイステップの解説、数式、実例、専門家のヒントをお届けしますので、もうしばらくお待ちください。
The cross product is a vector operation in three-dimensional space that takes two vectors and produces a third vector perpendicular to both of them. Its magnitude equals the area of the parallelogram spanned by the original two vectors, and its direction is determined by the right-hand rule. This makes the cross product a central tool in physics, engineering, graphics, robotics, and geometry. In plain English, it answers two questions at once: how much two vectors spread away from each other, and which perpendicular direction is associated with that spread. A cross product calculator is useful because the component formula can be easy to mix up by hand, especially when negative signs are involved. Students use it to check homework in linear algebra and mechanics. Engineers use the same operation for torque, angular momentum, magnetic-force direction, normal vectors on surfaces, and orientation calculations. Computer graphics systems use it to build surface normals and determine orientation in 3D space. The cross product exists specifically in three dimensions and is different from the dot product, which produces a scalar instead of a perpendicular vector. It also depends on order: swapping the vectors reverses the result. This calculator helps users enter two vectors, compute the perpendicular vector, and inspect its magnitude. That makes it practical both for learning the geometry and for confirming calculations in applied problems.
For A = (Ax, Ay, Az) and B = (Bx, By, Bz), A x B = (AyBz - AzBy, AzBx - AxBz, AxBy - AyBx). Magnitude = |A x B| = |A||B|sin(theta). Worked example: with A = (1,2,3) and B = (4,5,6), A x B = (2x6 - 3x5, 3x4 - 1x6, 1x5 - 2x4) = (-3, 6, -3).
- 1Enter the x, y, and z components of the first vector and the second vector.
- 2The calculator applies the determinant-style component formula for the three-dimensional cross product.
- 3It computes the resulting perpendicular vector using the signed component differences.
- 4The magnitude of that result is then calculated to show the size of the cross product.
- 5Interpret the direction using the right-hand rule because order matters in this operation.
- 6Use the result for geometry, mechanics, or graphics problems where a perpendicular vector is needed.
This is the classic classroom example for verifying the component formula.
The resulting vector is perpendicular to both inputs. Because the components include positive and negative terms, it is a good check against sign mistakes.
Perpendicular unit vectors produce the third basis direction.
This is the cleanest geometric example because the result points exactly along the positive z-axis. It also reinforces the right-hand rule.
Parallel vectors create no parallelogram area.
Because one vector is a scalar multiple of the other, they point in the same direction. That means the spread between them is zero, so the cross product vanishes.
Swapping the inputs reverses the direction.
This example is useful because the magnitude stays the same but the sign changes. It reminds users that cross product is anti-commutative.
Computing torque, angular momentum, and other vector quantities in mechanics. This application is commonly used by professionals who need precise quantitative analysis to support decision-making, budgeting, and strategic planning in their respective fields
Generating normal vectors for surfaces in computer graphics and geometry. Industry practitioners rely on this calculation to benchmark performance, compare alternatives, and ensure compliance with established standards and regulatory requirements
Checking orientation and perpendicular directions in robotics and engineering design. Academic researchers and students use this computation to validate theoretical models, complete coursework assignments, and develop deeper understanding of the underlying mathematical principles
Researchers use cross product computations to process experimental data, validate theoretical models, and generate quantitative results for publication in peer-reviewed studies, supporting data-driven evaluation processes where numerical precision is essential for compliance, reporting, and optimization objectives
Parallel vectors
{'title': 'Parallel vectors', 'body': 'If the input vectors are parallel or anti-parallel, the cross product is the zero vector and cannot define a unique normal direction.'} When encountering this scenario in cross product calculations, users should verify that their input values fall within the expected range for the formula to produce meaningful results. Out-of-range inputs can lead to mathematically valid but practically meaningless outputs that do not reflect real-world conditions.
Nearly parallel inputs
{'title': 'Nearly parallel inputs', 'body': 'When vectors are almost parallel, the magnitude becomes very small and numerical round-off can make the direction less stable in computation.'} This edge case frequently arises in professional applications of cross product where boundary conditions or extreme values are involved. Practitioners should document when this situation occurs and consider whether alternative calculation methods or adjustment factors are more appropriate for their specific use case.
Negative input values may or may not be valid for cross product depending on the domain context.
Some formulas accept negative numbers (e.g., temperatures, rates of change), while others require strictly positive inputs. Users should check whether their specific scenario permits negative values before relying on the output. Professionals working with cross product should be especially attentive to this scenario because it can lead to misleading results if not handled properly. Always verify boundary conditions and cross-check with independent methods when this case arises in practice.
| Property | Meaning | Practical effect |
|---|---|---|
| Magnitude | |A||B|sin(theta) | Gives parallelogram area |
| Direction | Perpendicular to both vectors | Use right-hand rule |
| Anti-commutative | A x B = -(B x A) | Order reverses the sign |
| Parallel vectors | Cross product is zero | No perpendicular spread |
| Orthogonal vectors | Magnitude is maximal for given lengths | sin(theta) = 1 |
What is the cross product used for?
It is used to find a vector perpendicular to two others and to compute oriented area in three-dimensional space. Common applications include torque, angular momentum, surface normals, and 3D graphics. In practice, this concept is central to cross product because it determines the core relationship between the input variables. Understanding this helps users interpret results more accurately and apply them to real-world scenarios in their specific context.
What does the magnitude of the cross product mean?
Its magnitude equals the area of the parallelogram formed by the two original vectors. If the vectors are parallel, that area is zero. In practice, this concept is central to cross product because it determines the core relationship between the input variables. Understanding this helps users interpret results more accurately and apply them to real-world scenarios in their specific context.
Why does order matter in a cross product?
Because A x B points in the opposite direction from B x A. The two results have the same magnitude but opposite sign and orientation. This matters because accurate cross product calculations directly affect decision-making in professional and personal contexts. Without proper computation, users risk making decisions based on incomplete or incorrect quantitative analysis. Industry standards and best practices emphasize the importance of precise calculations to avoid costly errors.
Can you take a cross product in two dimensions?
Not in the same vector-to-vector sense used in three dimensions. In 2D, related determinant ideas exist, but the standard cross product is fundamentally a 3D construction. This is an important consideration when working with cross product calculations in practical applications. The answer depends on the specific input values and the context in which the calculation is being applied. For best results, users should consider their specific requirements and validate the output against known benchmarks or professional standards.
What is the right-hand rule?
Point your fingers along the first vector and curl them toward the second vector. Your thumb then indicates the positive direction of the cross product. In practice, this concept is central to cross product because it determines the core relationship between the input variables. Understanding this helps users interpret results more accurately and apply them to real-world scenarios in their specific context.
When is the cross product zero?
It is zero when one vector is the zero vector or when the two vectors are parallel or anti-parallel. In those cases, the sine term becomes zero. This applies across multiple contexts where cross product values need to be determined with precision. Common scenarios include professional analysis, academic study, and personal planning where quantitative accuracy is essential. The calculation is most useful when comparing alternatives or validating estimates against established benchmarks.
How often should I verify a cross product result?
Verify it whenever sign matters, such as in torque, orientation, or normal-vector work. A quick dot-product check with each original vector can confirm perpendicularity. The process involves applying the underlying formula systematically to the given inputs. Each variable in the calculation contributes to the final result, and understanding their individual roles helps ensure accurate application. Most professionals in the field follow a step-by-step approach, verifying intermediate results before arriving at the final answer.
プロのヒント
Always verify your input values before calculating. For cross product, small input errors can compound and significantly affect the final result.
ご存知でしたか？
The mathematical principles behind cross product have practical applications across multiple industries and have been refined through decades of real-world use.