Skip to main content
Ch. 4 - Laws of Sines and Cosines; Vectors
Blitzer - Trigonometry 3rd Edition
Blitzer3rd EditionTrigonometryISBN: 9780137316601Not the one you use?Change textbook
Chapter 4, Problem 9

In Exercises 9–16, letu = 2i - j, v = 3i + j, and w = i + 4j.Find each specified scalar.u ⋅ (v + w)

Verified step by step guidance
1
First, find the vector sum \( v + w \). To do this, add the corresponding components of vectors \( v \) and \( w \).
Calculate \( v + w = (3i + j) + (i + 4j) \).
Combine the \( i \) components: \( 3i + i = 4i \).
Combine the \( j \) components: \( j + 4j = 5j \).
Now, compute the dot product \( u \cdot (v + w) \) by multiplying the corresponding components of \( u = 2i - j \) and \( v + w = 4i + 5j \), and then summing the results: \( (2 \times 4) + ((-1) \times 5) \).

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
3m
Was this helpful?

Key Concepts

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

Vector Addition

Vector addition involves combining two or more vectors to form a resultant vector. In this case, the vectors v and w are added together by adding their corresponding components. For example, if v = 3i + j and w = i + 4j, their sum is (3i + i) + (j + 4j) = 4i + 5j.
Recommended video:
05:29
Adding Vectors Geometrically

Dot Product

The dot product, or scalar product, of two vectors is a way to multiply them to obtain a scalar value. It is calculated by multiplying the corresponding components of the vectors and summing the results. For vectors u = 2i - j and v = 4i + 5j, the dot product is computed as (2 * 4) + (-1 * 5) = 8 - 5 = 3.
Recommended video:
05:40
Introduction to Dot Product

Scalar Result

A scalar result is a single numerical value obtained from operations involving vectors, such as the dot product. In the context of the given problem, the scalar result represents the magnitude of the projection of one vector onto another, providing insight into their directional relationship. This value is crucial for applications in physics and engineering.
Recommended video:
05:05
Multiplying Vectors By Scalars