Calculus 3 : Dot Product

Study concepts, example questions & explanations for Calculus 3

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Example Questions

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Example Question #1 : Dot Product

Evaluate the dot product between , and .

Possible Answers:

Correct answer:

Explanation:

All we need to do is multiply like components.

Example Question #2 : Dot Product

Evaluate the dot product of , and .

Possible Answers:

Correct answer:

Explanation:

All we need to do is multiply the like components and add them together.

Example Question #3 : Dot Product

Find the dot product of the following vectors:

Possible Answers:

Correct answer:

Explanation:

To find the dot product between two vectors 

we calculate

so for 

we have

Example Question #4 : Dot Product

What is the length of the vector

?

Possible Answers:

Correct answer:

Explanation:

We can compute the length of a vector by taking the square root of the dot product of  and , so the length of  is:

Example Question #5 : Dot Product

Find the dot product of the following vectors:

Possible Answers:

Correct answer:

Explanation:

To find the dot product between two vectors 

we calculate

so for 

we have

Example Question #1 : Dot Product

What is the length of the vector

?

Possible Answers:

Correct answer:

Explanation:

We can compute the length of a vector by taking the square root of the dot product of  and , so the length of  is:

Example Question #7 : Dot Product

Which of the following cannot be used as a definition of the dot product of two real-valued vectors?

Possible Answers:

They may all be used

, where  is the angle between .

Correct answer:

Explanation:

 is not correct. This is saying effectively to add all the components of the two vectors together. The other two definitions are commonly used in computing angles between vectors and other objects, and can also be derived from each other.

Example Question #2 : Dot Product

Which of the following is true concerning the dot product of two vectors?

Possible Answers:

The dot product of two vectors is never negative.

 if and only if  are orthogonal.

None of the other statements are true.

The dot product of two vectors is never a scalar.

 is well-defined as long as each vector is the same dimension

Correct answer:

 if and only if  are orthogonal.

Explanation:

This statement is true; it can be derived from the definition by setting the acute angle between the vectors to be  ; the requirement for orthogonality. Additionally, if either vector has length , the vectors are still said to be orthogonal.

Example Question #3 : Dot Product

What is the dot product of vectors  and ?

Possible Answers:

Correct answer:

Explanation:

Let vector  be represented as   and vector   be represented as  .

 

The dot product of the vectors   and  is .

In this problem

Example Question #10 : Dot Product

What is the dot product of vectors  and ?

Possible Answers:

Does not exist

Correct answer:

Explanation:

Let vector  be represented as   and vector   be represented as  .

 

The dot product of the vectors   and  is .

In this problem

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