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Ch. 4 - Laws of Sines and Cosines; Vectors
Chapter 4, Problem 4.14

Let v be the vector from initial point P₁ to terminal point P₂. Write v in terms of i and j.


P₁ = (2, -5), P₂ = (-6, 6)

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1
Identify the coordinates of the initial point \( P_1 = (2, -5) \) and the terminal point \( P_2 = (-6, 6) \).
To find the vector \( \mathbf{v} \) from \( P_1 \) to \( P_2 \), calculate the difference in the x-coordinates: \( x_2 - x_1 = -6 - 2 \).
Calculate the difference in the y-coordinates: \( y_2 - y_1 = 6 - (-5) \).
Express the vector \( \mathbf{v} \) in terms of \( \mathbf{i} \) and \( \mathbf{j} \) using the differences calculated: \( \mathbf{v} = (x_2 - x_1)\mathbf{i} + (y_2 - y_1)\mathbf{j} \).
Substitute the calculated differences into the expression for \( \mathbf{v} \) to write it in terms of \( \mathbf{i} \) and \( \mathbf{j} \).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Vectors

A vector is a mathematical object that has both magnitude and direction. In a two-dimensional space, a vector can be represented as an ordered pair of coordinates, indicating its position relative to a reference point. For example, the vector from point P₁ to P₂ can be expressed as the difference between their coordinates.
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Unit Vectors i and j

In a Cartesian coordinate system, the unit vectors i and j represent the directions along the x-axis and y-axis, respectively. The vector i is typically represented as (1, 0), while j is represented as (0, 1). Any vector in the plane can be expressed as a linear combination of these unit vectors, allowing for a clear representation of its components.
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i & j Notation

Vector Subtraction

Vector subtraction involves finding the difference between two vectors, which can be visualized as moving from one point to another in the coordinate plane. For points P₁ and P₂, the vector v can be calculated by subtracting the coordinates of P₁ from those of P₂. This operation yields a new vector that indicates the direction and distance from P₁ to P₂.
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