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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 3c

In Exercises 1–4, u and v have the same direction. In each exercise: Is u = v? Explain.

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1
Understand that two vectors \( \mathbf{u} \) and \( \mathbf{v} \) having the same direction means they are scalar multiples of each other. This implies \( \mathbf{u} = k \mathbf{v} \) for some scalar \( k > 0 \).
Recall that for \( \mathbf{u} = \mathbf{v} \) to be true, both the magnitude (length) and direction of \( \mathbf{u} \) and \( \mathbf{v} \) must be exactly the same.
Since \( \mathbf{u} \) and \( \mathbf{v} \) have the same direction, check if their magnitudes are equal by comparing \( |\mathbf{u}| \) and \( |\mathbf{v}| \).
If \( |\mathbf{u}| = |\mathbf{v}| \), then \( k = 1 \) and \( \mathbf{u} = \mathbf{v} \). Otherwise, if \( |\mathbf{u}| \neq |\mathbf{v}| \), then \( \mathbf{u} \neq \mathbf{v} \) even though they point in the same direction.
Summarize your conclusion by stating that having the same direction does not guarantee \( \mathbf{u} = \mathbf{v} \); equality requires both direction and magnitude to be identical.

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이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
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주요 개념

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

Vector Direction

Vector direction refers to the orientation of a vector in space, independent of its magnitude. Two vectors have the same direction if they lie along the same line or parallel lines, pointing either the same way or exactly opposite. Understanding direction is crucial to compare vectors beyond just their lengths.
추천 영상:
05:13
Finding Direction of a Vector

Vector Equality

Two vectors are equal if and only if they have the same magnitude and the same direction. Even if vectors share the same direction, they are not equal unless their lengths are identical. This concept helps determine when vectors represent the same quantity.
추천 영상:
03:48
Introduction to Vectors

Scalar Multiplication of Vectors

Scalar multiplication changes a vector's magnitude without altering its direction, unless the scalar is negative, which reverses the direction. Recognizing how scaling affects vectors is essential to understand when vectors with the same direction differ in magnitude and thus are not equal.
추천 영상:
05:05
Multiplying Vectors By Scalars