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Ch. 4 - Laws of Sines and Cosines; Vectors
Blitzer - Trigonometry 3rd Edition
Blitzer3rd EditionTrigonometryISBN: 9780137316601당신이 사용하는 게 아니라요?교과서 변경
4장, 문제 33

In Exercises 33–38, find projᵥᵥ v. Then decompose v into two vectors, v₁ and v₂, where v₁ is parallel to w and v₂ is orthogonal to w. v = 3i - 2j, w = i - j

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Identify the vectors \( \mathbf{v} = 3\mathbf{i} - 2\mathbf{j} \) and \( \mathbf{w} = \mathbf{i} - \mathbf{j} \).
Recall the formula for the projection of \( \mathbf{v} \) onto \( \mathbf{w} \): \[ \text{proj}_{\mathbf{w}} \mathbf{v} = \left( \frac{\mathbf{v} \cdot \mathbf{w}}{\mathbf{w} \cdot \mathbf{w}} \right) \mathbf{w} \] where \( \cdot \) denotes the dot product.
Calculate the dot product \( \mathbf{v} \cdot \mathbf{w} \) by multiplying corresponding components and summing: \[ \mathbf{v} \cdot \mathbf{w} = (3)(1) + (-2)(-1) \]
Calculate the dot product \( \mathbf{w} \cdot \mathbf{w} \) similarly: \[ \mathbf{w} \cdot \mathbf{w} = (1)(1) + (-1)(-1) \]
Use the values from the dot products to find \( \text{proj}_{\mathbf{w}} \mathbf{v} \) by multiplying the scalar \( \frac{\mathbf{v} \cdot \mathbf{w}}{\mathbf{w} \cdot \mathbf{w}} \) by the vector \( \mathbf{w} \). Then, find \( \mathbf{v}_1 = \text{proj}_{\mathbf{w}} \mathbf{v} \) (parallel component) and \( \mathbf{v}_2 = \mathbf{v} - \mathbf{v}_1 \) (orthogonal component).

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Vector Projection

Vector projection of v onto w, denoted proj_w v, is the component of v that points in the direction of w. It is calculated using the formula proj_w v = (v · w / w · w) w, where '·' denotes the dot product. This concept helps in finding how much of one vector lies along another.
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Introduction to Vectors

Dot Product of Vectors

The dot product is an algebraic operation that takes two vectors and returns a scalar. It is computed as v · w = v₁w₁ + v₂w₂ for 2D vectors. The dot product is essential for finding projections and determining angles between vectors.
추천 영상:
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Introduction to Dot Product

Vector Decomposition into Parallel and Orthogonal Components

Any vector v can be decomposed into two components: v₁ parallel to w and v₂ orthogonal to w. Here, v₁ = proj_w v, and v₂ = v - v₁. This decomposition is useful in many applications, such as resolving forces or simplifying vector problems.
추천 영상:
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Position Vectors & Component Form