AnswersPrecalculusSolving Trigonometric Equations

Solving Trigonometric Equations — Unit test Answers

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1
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What is the value of 1 − 2sin2(105°)?

A
Negative StartFraction StartRoot 3 EndRoot Over 2 EndFraction
Option A
B
Negative one-half
Option B
C
One-half
Option C
D
StartFraction StartRoot 3 EndRoot Over 2 EndFraction
Option D
2
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Read the proof.

Question illustration
A
tangent double angle identity
Option A
B
tangent sum identity
Option B
C
tangent double angle identity
Option C
D
tangent sum identity
Option D
3

What is the solution to the trigonometric inequality over the interval radians?

Question illustration
A
0 is less than equal to x and x is less than StartFraction pi over 4 EndFraction
Option A
B
and
Option B
C
x is greater than StartFraction pi over 4 EndFraction but less than StartFraction 5pi over 4 EndFraction
Option C
D
and
Option D
4

To solve the trigonometric inequality over the interval radians, Gabby performed the following steps, first simplifying the inequality and then setting both sides equal to y and graphing the equations. Step 1: Step 2: Step 3: Step 4: Step 5: Step 6: In which step did she first make an error, and what was the error?

Question illustration
A
She first made an error in step 3 because she should not have subtracted and added to the right side of the inequality.
Option A
B
She first made an error in step 4 because the simplified form of the inequality should have been instead of .
Option B
C
She first made an error in step 5 because she did not correctly graph .
Option C
D
She first made an error in step 6 because she chose the wrong interval in which the graph of one equation is at or above the graph of the other equation.
5

For 0 ≤ x < 2π, which of the following solves 2cos + 1 = 0?

Question illustration
A
Left-brace StartFraction 4 pi Over 3 EndFraction right-brace
Option A
B
Left-brace StartFraction 5 pi Over 3 EndFraction right-brace
Option B
C
Left-brace StartFraction pi Over 3 EndFraction, StartFraction 2 pi Over 3 EndFraction right-brace
Option C
D
Left-brace StartFraction pi Over 3 EndFraction, StartFraction 5 pi Over 3 EndFraction right-brace
Option D
6

According to your graphing calculator, what is the approximate solution to the trigonometric inequality over the interval radians?

Question illustration
A
x is greater than equal to 0 but less than 0.7896
Option A
B
x is greater than equal to 0 but less than 0.9799
Option B
C
x is greater than equal to 0 but less than 0.9870
Option C
D
x is greater than equal to 0 but less than 1.2249
Option D

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