Calculus 3 : Vectors and Vector Operations

Study concepts, example questions & explanations for Calculus 3

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Example Questions

Example Question #1 : Parametric Curves

Find the length of the parametric curve described by

from  to .

 

Possible Answers:

None of the other answers

Correct answer:

Explanation:

There are several ways to solve this problem, but the most effective would be to notice that we can derive the following-

Hence

Therefore our curve is a circle of radius , and it's circumfrence is . But we are only interested in half that circumfrence ( is from  to , not .), so our answer is .

 

Alternatively, we could've found the length using the formula

.

Example Question #2 : Parametric Curves

Find the coordinates of the curve function


when .

Possible Answers:

Correct answer:

Explanation:

To find the coordinates, we set  into the curve function.

We get

and thus

Example Question #1 : Parametric Curves

Find the coordinates of the curve function

when

Possible Answers:

Correct answer:

Explanation:

To find the coordinates, we evaluate the curve function for 

As such,

Example Question #4 : Parametric Curves

Find the coordinates of the curve function 

 when 

Possible Answers:

Correct answer:

Explanation:

To find the coordinates, we evaluate the curve function for

As such,

Example Question #5 : Parametric Curves

Find the equation of the line passing through the two points, given in parametric form:

Possible Answers:

Correct answer:

Explanation:

To find the equation of the line passing through these two points, we must first find the vector between them:

This was done by finding the difference between the x, y, and z components for the vectors. (This can be done in either order, it doesn't matter.)

Now, pick a point to be used in the equation of the line, as the initial point. We write the equation of line as follows:

The choice of initial point is arbitrary. 

Example Question #4 : Parametric Curves

Find the coordinate of the parametric curve when 

 

Possible Answers:

Correct answer:

Explanation:

To find the coordinates of the parametric curve we plug in for

.

As such the coordinates are

Example Question #1 : Cross Product

Let , and .

Find .

Possible Answers:

Correct answer:

Explanation:

We are trying to find the cross product between  and .

Recall the formula for cross product.

If  , and , then

.

Now apply this to our situation.

Example Question #1 : Cross Product

Let , and .

Find .

Possible Answers:

Correct answer:

Explanation:

We are trying to find the cross product between  and .

Recall the formula for cross product.

If  , and , then

.

Now apply this to our situation.

Example Question #3 : Cross Product

True or False: The cross product can only be taken of two 3-dimensional vectors.

Possible Answers:

False

True

Correct answer:

True

Explanation:

This is true. The cross product is defined this way. The dot product however can be taken for two vectors of dimension n (provided that both vectors are the same dimension).

Example Question #4 : Cross Product

Which of the following choices is true?

Possible Answers:

Correct answer:

Explanation:

By definition, the order of the dot product of two vectors does not matter, as the final output is a scalar.  However, the cross product of two vectors will change signs depending on the order that they are crossed.  Therefore 

.

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