SAT II Math II : Solving Trigonometric Functions

Study concepts, example questions & explanations for SAT II Math II

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Example Questions

Example Question #1 : Solving Trigonometric Functions

Give the period of the graph of the equation

\displaystyle f(x) = \frac{2}{9} \sin 8 x

Possible Answers:

The correct answer is not among the other choices.

\displaystyle \frac{2}{9}

\displaystyle \frac{1}{8}

\displaystyle \frac{9}{2}

\displaystyle 8

Correct answer:

The correct answer is not among the other choices.

Explanation:

The period of the graph of a sine function \displaystyle f(x)= A \sin Bx is \displaystyle \frac{2 \pi}{B}, or \displaystyle 2 \pi \div B.

Since \displaystyle B= 8,

\displaystyle 2 \pi \div 8 = \frac{\pi }{4}.

This answer is not among the given choices.

Example Question #2 : Solving Trigonometric Functions

If \displaystyle f(x)=2sin(x)+cos(x), what must \displaystyle f(\frac{\pi}{4}) be?

Possible Answers:

\displaystyle 3\sqrt{2}

\displaystyle 4\sqrt2

\displaystyle \textup{The answer is not given.}

\displaystyle \frac{\sqrt2}{2}+2

\displaystyle \frac{3\sqrt2}{2}

Correct answer:

\displaystyle \frac{3\sqrt2}{2}

Explanation:

Evaluate each trig function at the specified angle.

\displaystyle sin(\frac{\pi}{4}) = \frac{\sqrt{2}}{2}

\displaystyle cos(\frac{\pi}{4}) = \frac{\sqrt{2}}{2}

Replace the terms into the function.

\displaystyle f(\frac{\pi}{4})=2sin(\frac{\pi}{4})+cos(\frac{\pi}{4}) = 2(\frac{\sqrt{2}}{2})+\frac{\sqrt{2}}{2}

Combine like-terms.

The answer is:  \displaystyle \frac{3\sqrt2}{2}

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