The following are all angle measures (in radians, rounded to the nearest hundredth) whose cosine is −0.65 .Which is the principal value of arccos(−0.65)?Choose 1 answer:(A) −10.29(B) −4.00(C) 2.28(D) 8.56
Q. The following are all angle measures (in radians, rounded to the nearest hundredth) whose cosine is −0.65 .Which is the principal value of arccos(−0.65)?Choose 1 answer:(A) −10.29(B) −4.00(C) 2.28(D) 8.56
Identify Quadrant: The principal value of arccos(x) is the unique value y in the range [0,π] such that cos(y)=x. Since −0.65 is negative, the principal value must be in the second quadrant where cosine is negative.
Find Angle: To find the principal value of arccos(−0.65), we use a calculator or a trigonometric table to find the angle whose cosine is −0.65. Remember that the principal value will be in the range [0,π].
Calculate Value: Using a calculator, we find that arccos(−0.65)≈2.28 radians. This is the angle in the second quadrant and falls within the principal range [0,π].
Select Correct Option: Looking at the options provided, (C) 2.28 is the only value that is positive and falls within the range [0,π]. Therefore, this must be the principal value of arccos(−0.65).
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