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Select the answer which is equivalent to the given expression using your calculator.

csc(arccos ((sqrt15)/(4)))

(4)/(sqrt15)
4

(sqrt15)/(4)

sqrt15

Select the answer which is equivalent to the given expression using your calculator.\newlinecsc(arccos154) \csc \left(\arccos \frac{\sqrt{15}}{4}\right) \newline415 \frac{4}{\sqrt{15}} \newline44\newline154 \frac{\sqrt{15}}{4} \newline15 \sqrt{15}

Full solution

Q. Select the answer which is equivalent to the given expression using your calculator.\newlinecsc(arccos154) \csc \left(\arccos \frac{\sqrt{15}}{4}\right) \newline415 \frac{4}{\sqrt{15}} \newline44\newline154 \frac{\sqrt{15}}{4} \newline15 \sqrt{15}
  1. Understand relationship: Understand the relationship between arccos\text{arccos} and cosine. The arccos\text{arccos} function is the inverse of the cosine function. This means that if x=arccos(y)x = \text{arccos}(y), then y=cos(x)y = \cos(x). Therefore, if we have arccos(154)\text{arccos}(\frac{\sqrt{15}}{4}), we can say that cos(θ)=154\cos(\theta) = \frac{\sqrt{15}}{4}, where θ\theta is the angle whose cosine is 154\frac{\sqrt{15}}{4}.
  2. Use Pythagorean identity: Use the Pythagorean identity to find sin(θ)\sin(\theta). Since cos2(θ)+sin2(θ)=1\cos^2(\theta) + \sin^2(\theta) = 1, we can find sin(θ)\sin(\theta) by rearranging the identity to sin2(θ)=1cos2(θ)\sin^2(\theta) = 1 - \cos^2(\theta). We know cos(θ)=(15)/4\cos(\theta) = (\sqrt{15})/4, so we can calculate sin(θ)\sin(\theta) as follows:\newlinesin2(θ)=1((15)/4)2\sin^2(\theta) = 1 - ((\sqrt{15})/4)^2\newlinesin2(θ)=1(15/16)\sin^2(\theta) = 1 - (15/16)\newlinesin2(θ)=(16/16)(15/16)\sin^2(\theta) = (16/16) - (15/16)\newlinesin2(θ)=1/16\sin^2(\theta) = 1/16\newlinecos2(θ)+sin2(θ)=1\cos^2(\theta) + \sin^2(\theta) = 100\newlinecos2(θ)+sin2(θ)=1\cos^2(\theta) + \sin^2(\theta) = 111 or cos2(θ)+sin2(θ)=1\cos^2(\theta) + \sin^2(\theta) = 122\newlineSince cos2(θ)+sin2(θ)=1\cos^2(\theta) + \sin^2(\theta) = 133 always gives an angle in the range cos2(θ)+sin2(θ)=1\cos^2(\theta) + \sin^2(\theta) = 144, where sine is non-negative, we take the positive value cos2(θ)+sin2(θ)=1\cos^2(\theta) + \sin^2(\theta) = 111.
  3. Calculate sin(θ)\sin(\theta): Calculate csc(θ)\csc(\theta) using the definition of cosecant. Cosecant is the reciprocal of sine, so csc(θ)=1sin(θ)\csc(\theta) = \frac{1}{\sin(\theta)}. We have found that sin(θ)=14\sin(\theta) = \frac{1}{4}, so: csc(θ)=1(14)\csc(\theta) = \frac{1}{(\frac{1}{4})} csc(θ)=4\csc(\theta) = 4
  4. Conclude csc(θ)\csc(\theta): Conclude that csc(arccos(154))\csc(\arccos(\frac{\sqrt{15}}{4})) is equivalent to 44. Since we have calculated csc(θ)\csc(\theta) to be 44, where θ\theta is the angle whose cosine is 154\frac{\sqrt{15}}{4}, we can say that csc(arccos(154))=4\csc(\arccos(\frac{\sqrt{15}}{4})) = 4.

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