Precalculus : Pre-Calculus

Study concepts, example questions & explanations for Precalculus

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Example Questions

Example Question #1 : Trigonometric Graphs (All Six)

Which of the trigonometric functions is represented by this graph?

Cscx

Possible Answers:

y = sec x

y = tan x

y = cot x

y = csc x

Correct answer:

y = csc x

Explanation:

This graph is the graph of y = csc x. The domain of this function is all real numbers except \(\displaystyle n\cdot \pi\) where n is any integer. In other words, there are vertical asymptotes at all multiples of \(\displaystyle \pi\). The range of this function is \(\displaystyle y\leq -1, y\geq 1\). The period of this function is \(\displaystyle 2\pi\).

Example Question #2 : Trigonometric Graphs (All Six)

Which of the following functions is represented by this graph?


Cotx

Possible Answers:

y = cot x

y = csc x

y = sec x

y = tan x

Correct answer:

y = cot x

Explanation:

This graph is the graph of y = cot x. The domain of this function is all real numbers except \(\displaystyle n\cdot \pi\) where n is any integer. In other words, there are vertical asymptotes at all multiples of \(\displaystyle \pi\). The range of this function is \(\displaystyle \left ( -\infty, \infty \right )\). The period of this function is \(\displaystyle \pi\).

Example Question #3 : Trigonometric Graphs (All Six)

Which of the following functions is represented by this graph?


Secx

Possible Answers:

y = tan x

y = sec x

y = csc x

y = cot x

Correct answer:

y = sec x

Explanation:

This graph is the graph of y = sec x. The domain of this function is all real numbers except \(\displaystyle \frac{\pi}{2} + n\pi\) where n is any integer. In other words, there are vertical asymptotes at \(\displaystyle \frac{\pi}{2}\) , \(\displaystyle \frac{3\pi}2{}\)\(\displaystyle \frac{5\pi}{2}\), and so on. The range of this function is \(\displaystyle y\leq -1, y\geq 1\). The period of this function is \(\displaystyle 2\pi.\)

Example Question #4 : Trigonometric Graphs (All Six)

Which of the following functions is represented by this graph?


Tan x

Possible Answers:

y = csc x

y = cot x

y = sec x

y = tan x

Correct answer:

y = tan x

Explanation:

This graph is the graph of y = tan x. The domain of this function is all real numbers except \(\displaystyle \frac{\pi}{2}+n\pi\) where n is any integer. In other words, there are vertical asymptotes at \(\displaystyle \frac{\pi}{2}, \frac{3\pi}{2}, \frac{5\pi}{2}\), and so on. The range of this function is \(\displaystyle \left ( -\infty, \infty \right )\). The period of this function is \(\displaystyle \pi\).

Example Question #4 : Trigonometric Graphs (All Six)

Which of the following functions has a y-intercept of \(\displaystyle 1\)

Possible Answers:

\(\displaystyle y = \sin(x)\)

\(\displaystyle y = \cot(x)\)

\(\displaystyle y = \tan(x)\)

\(\displaystyle y = \csc(x)\)

\(\displaystyle y = \cos(x)\)

Correct answer:

\(\displaystyle y = \cos(x)\)

Explanation:

The y-intercept of a function is found by substituting \(\displaystyle x = 0\). When we do this to each, we can determine the y-intercept. Don't forget your unit circle! 

\(\displaystyle y = sin(0) = 0\)

\(\displaystyle y = cos(0) = 1\)

\(\displaystyle y = csc(0) = undefined\)

\(\displaystyle y = tan(0)= 0\)

\(\displaystyle y = cot(0) = undefined\)

Thus, the function with a y-intercept of \(\displaystyle 1\) is \(\displaystyle y = cos(x)\)

Example Question #5 : Trigonometric Graphs (All Six)

Which of the following functions is represented by this graph?


Cosine

Possible Answers:

y = sin(x)

y = csc(x)

y = tan(x)

y = sec(x)

y = cos(x)

Correct answer:

y = cos(x)

Explanation:

This graph is the graph of y = cos x. The domain of this function is all real numbers. The range of this function is \(\displaystyle -1\leq y\leq 1\). The period of this function is \(\displaystyle 2\pi\).

Example Question #6 : Trigonometric Graphs (All Six)

Which of the following functions is represented by this graph?


Sinx

Possible Answers:

y = tan x

y = sec x

y = cos x

y = csc x

y = sin x

Correct answer:

y = sin x

Explanation:

This graph is the graph of y = sin x. The domain of this function is all real numbers. The range of this function is \(\displaystyle -1\leq y\leq 1\). The period of this function is \(\displaystyle 2\pi\).

Example Question #7 : Trigonometric Graphs (All Six)

True or false: If you translate a secant function \(\displaystyle \pi\) units to the left along the x-axis, you will have a cosecant curve.

Possible Answers:

True

False

Correct answer:

False

Explanation:

This is false. While the graphs of secant and cosecant functions are related, in order to turn a secant function into a cosecant function, you'd need to translate the original graph \(\displaystyle \frac{\pi}{2}\) units to the right to obtain a cosecant graph.

Example Question #7 : Trigonometric Graphs (All Six)

Where does the tangent function intercept the x-axis?

Possible Answers:

\(\displaystyle x=n\pi\)

\(\displaystyle x=\pi\)

x= all real numbers

\(\displaystyle x=2n\pi\)

No solution

Correct answer:

\(\displaystyle x=n\pi\)

Explanation:

Because the tangent function is periodic, it intercepts the x-axis in infinitely many places. We can see several of these in the graph below:

Tan x

In the photo, we can see that the function is intercepting the x-axis at \(\displaystyle x=-2\pi, -\pi, 0, \pi.\) Generalizing this, we can say that the tangent function intercepts the x-axis for \(\displaystyle x=n\pi\) for all values of n such that n is an integer.

Example Question #8 : Trigonometric Graphs (All Six)

True or false: If you translate a sine curve 90o to the left along the x-axis, you will have a cosine curve.

Possible Answers:

False

True

Correct answer:

True

Explanation:

This is true! Notice the similarity of the shape between the graphs, but that they intercept the x-axis at different spots, and their peaks and valleys are at different spots.

y=sin(x), passes through the point (0,0)

Sinx

y=cos(x), passes through the point (0,1)

Cosine

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