AP Calculus BC : Functions, Graphs, and Limits

Study concepts, example questions & explanations for AP Calculus BC

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Example Questions

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Example Question #1 :Parametric Form

Rewrite as a Cartesian equation:

Possible Answers:

Correct answer:

Explanation:

So

or

We are restrictingto values on, sois nonnegative; we choose

.

Also,

So

or

We are restrictingto values on, sois nonpositive; we choose

or equivalently,

to makenonpositive.

Then,

and

Example Question #1 :Parametric, Polar, And Vector Functions

Rewrite as a Cartesian equation:

Possible Answers:

Correct answer:

Explanation:

, so

This makes the Cartesian equation

.

Example Question #3 :Parametric, Polar, And Vector Functions

Ifand, what isin terms of(rectangular form)?

Possible Answers:

Correct answer:

Explanation:

Givenand, we can findin terms ofby isolatingin both equations:

Since both of these transformations equal, we can set them equal to each other:

Example Question #4 :Parametric, Polar, And Vector Functions

Givenand, what is the arc length between?

Possible Answers:

Correct answer:

Explanation:

In order to find the arc length, we must use the arc length formula for parametric curves:

.

Givenand, we can use using the Power Rule

for all, to derive

and

.

Plugging these values and our boundary values forinto the arc length equation, we get:

Now, using the Power Rule for Integrals

for all,

we can determine that:

Example Question #5 :Parametric, Polar, And Vector Functions

Givenand, what is the length of the arc from?

Possible Answers:

Correct answer:

Explanation:

In order to find the arc length, we must use the arc length formula for parametric curves:

.

Givenand, we can use using the Power Rule

for all, to derive

and

.

Plugging these values and our boundary values forinto the arc length equation, we get:

Now, using the Power Rule for Integrals

for all,

we can determine that:

Example Question #6 :Parametric, Polar, And Vector Functions

Find the length of the following parametric curve

,,.

Possible Answers:

Correct answer:

Explanation:

The length of a curve is found using the equation

We use the product rule,

, whenandare functions of,

the trigonometric rule,

and

and exponential rule,

to findand.

In this case

,

The length of this curve is

Using the identity

Using the identity

Using the trigonometric identitywhereis a constant and

Using the exponential rule,

Using the exponential rule,, gives us the final solution

Example Question #1 :Parametric Form

Finddy/dxat the point corresponding to the given value of the parameter without eliminating the parameter:



Possible Answers:

Correct answer:

Explanation:

The formula fordy/dxfor parametric equations is given as:

From the problem statement:

If we plug these into the above equation we end up with:

If we plug in our given value for t, we end up with:

This is one of the answer choices.

Example Question #1 :Graphing Polar Form

Draw the graph offrom.

Possible Answers:

R_sinx_1

R_cosx

R_sin2x

R_sinx

Faker_cosx

Correct answer:

R_sinx

Explanation:

Betweenand, the radius approachesfrom.

Fromtothe radius goes fromto.

Betweenand, the curve is redrawn in the opposite quadrant, the first quadrant as the radius approaches.

Fromand, the curve is redrawn in the second quadrant as the radius approachesfrom.

Example Question #8 :Parametric, Polar, And Vector Functions

Draw the graph ofwhere.

Possible Answers:

R_cos2x

R_sin2x

R_sinx_1

Faker_cosx

R_sinx

Correct answer:

R_sin2x

Explanation:

Because this function has a period of, the amplitude of the graphappear at a reference angle of(angles halfway between the angles of the axes).

Betweenandthe radius approaches 1 from 0.

Betweenand, the radius approaches 0 from 1.

Fromtothe radius approaches -1 from 0 and is drawn in the opposite quadrant, the fourth quadrant because it has a negative radius.

Betweenand, the radius approaches 0 from -1, and is also drawn in the fourth quadrant.

Fromand, the radius approaches 1 from 0. Betweenand, the radius approaches 0 from 1.

Then betweenandthe radius approaches -1 from 0. Because it is a negative radius, it is drawn in the opposite quadrant, the second quadrant. Likewise, as the radius approaches 0 from -1. Betweenand, the curve is drawn in the second quadrant.

Example Question #9 :Parametric, Polar, And Vector Functions

Graphwhere.

Possible Answers:

R2_cos2x

R_cos2x

R_sin2x

R2_sin2x

R_cosx

Correct answer:

R2_cos2x

Explanation:

Taking the graph of, we only want the areas in the positive first quadrant because the radius is squared and cannot be negative.

This leaves us with the areas fromto,to, andto.

Then, when we take the square root of the radius, we get both a positive and negative answer with a maximum and minimum radius of.

To draw the graph, the radius is 1 atand traces to 0 at. As well, the negative part of the radius starts at -1 and traces to zero in the opposite quadrant, the third quadrant.

Fromto, the curves are traced from 0 to 1 and 0 to -1 in the fourth quadrant. Following this pattern, the graph is redrawn again from the areas included into.

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