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AlexFokin [52]
3 years ago
14

If cos x = −6/7, and 90° < x < 180°, what is cos⁡(2x)?

Mathematics
1 answer:
Naddik [55]3 years ago
6 0

Recall the double angle identity:

\cos2x=\cos^2x-\sin^2x=2\cos^2x-1

Then

\cos2x=2\left(-\dfrac67\right)^2-1=\dfrac{23}{49}

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A surveyor found the angle of elevation from the ground to the top of the building at two locations 20 feet apart as shown below
Serga [27]

Applying the sine ratio and law of sines, the correct measurements are:

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<h3>What is the Sine Ratio?</h3>

Sine ratio that can be used to determine the side length of a right triangle is, sin ∅ = opposite side/hypotenuse.

Find c using the law of sines:

C = 33°

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c = ?

Using the law of sines, b/sin B = c/sin C, we have:

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h = (sin 48)(42.09)

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The correct measurements are:

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brainly.com/question/2920412

#SPJ1

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