Q. Select the answer which is equivalent to the given expression using your calculator.csc(arccos415)154441515
Understand relationship: Understand the relationship between arccos and cosine. The arccos function is the inverse of the cosine function. This means that if x=arccos(y), then y=cos(x). Therefore, if we have arccos(415), we can say that cos(θ)=415, where θ is the angle whose cosine is 415.
Use Pythagorean identity: Use the Pythagorean identity to find sin(θ). Since cos2(θ)+sin2(θ)=1, we can find sin(θ) by rearranging the identity to sin2(θ)=1−cos2(θ). We know cos(θ)=(15)/4, so we can calculate sin(θ) as follows:sin2(θ)=1−((15)/4)2sin2(θ)=1−(15/16)sin2(θ)=(16/16)−(15/16)sin2(θ)=1/16cos2(θ)+sin2(θ)=10cos2(θ)+sin2(θ)=11 or cos2(θ)+sin2(θ)=12Since cos2(θ)+sin2(θ)=13 always gives an angle in the range cos2(θ)+sin2(θ)=14, where sine is non-negative, we take the positive value cos2(θ)+sin2(θ)=11.
Calculate sin(θ): Calculate csc(θ) using the definition of cosecant. Cosecant is the reciprocal of sine, so csc(θ)=sin(θ)1. We have found that sin(θ)=41, so: csc(θ)=(41)1csc(θ)=4
Conclude csc(θ): Conclude that csc(arccos(415)) is equivalent to 4. Since we have calculated csc(θ) to be 4, where θ is the angle whose cosine is 415, we can say that csc(arccos(415))=4.
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