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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 46

In Exercises 39–46, find the unit vector that has the same direction as the vector v.


v = i - j

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Identify the given vector \( \mathbf{v} = \mathbf{i} - \mathbf{j} \), which can be written in component form as \( \mathbf{v} = \langle 1, -1 \rangle \).
Calculate the magnitude (length) of the vector \( \mathbf{v} \) using the formula \( \| \mathbf{v} \| = \sqrt{v_x^2 + v_y^2} \). Substitute the components to get \( \| \mathbf{v} \| = \sqrt{1^2 + (-1)^2} \).
Simplify the expression under the square root to find the magnitude \( \| \mathbf{v} \| \).
Find the unit vector \( \mathbf{u} \) in the same direction as \( \mathbf{v} \) by dividing each component of \( \mathbf{v} \) by its magnitude: \( \mathbf{u} = \frac{1}{\| \mathbf{v} \|} \mathbf{v} = \left\langle \frac{1}{\| \mathbf{v} \|}, \frac{-1}{\| \mathbf{v} \|} \right\rangle \).
Express the unit vector \( \mathbf{u} \) in terms of \( \mathbf{i} \) and \( \mathbf{j} \) as \( \mathbf{u} = \frac{1}{\| \mathbf{v} \|} \mathbf{i} - \frac{1}{\| \mathbf{v} \|} \mathbf{j} \).

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주요 개념

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

Vector Direction

The direction of a vector is the orientation it points to in space, independent of its length. Two vectors have the same direction if one is a scalar multiple of the other. Understanding direction is essential to find a unit vector that aligns with the original vector.
추천 영상:
05:13
Finding Direction of a Vector

Vector Magnitude (Length)

The magnitude of a vector is its length, calculated using the square root of the sum of the squares of its components. For vector v = i - j, the magnitude is √(1² + (-1)²) = √2. This value is used to normalize the vector.
추천 영상:
04:44
Finding Magnitude of a Vector

Unit Vector

A unit vector has a magnitude of 1 and points in a specific direction. To find a unit vector in the same direction as v, divide each component of v by its magnitude. This process scales the vector to length one without changing its direction.
추천 영상:
04:04
Unit Vector in the Direction of a Given Vector