The following are all angle measures (in radians, rounded to the nearest hundredth) whose cosine is −0.26.Which is the principal value of cos−1(−0.26) ?Choose 1 answer:(A) −17.02(B) −10.73(C) −4.45(D) 1.83
Q. The following are all angle measures (in radians, rounded to the nearest hundredth) whose cosine is −0.26.Which is the principal value of cos−1(−0.26) ?Choose 1 answer:(A) −17.02(B) −10.73(C) −4.45(D) 1.83
Consider Range of Cosine Inverse: To find the principal value of the inverse cosine function, we need to consider the range of the principal values for the cosine inverse, which is from 0 to π for positive values and from −π to 0 for negative values. Since −0.26 is a negative value, we are looking for an angle in the third or fourth quadrant where the cosine is negative.
Identify Quadrant for Principal Value: The principal value of cos−1(−0.26) will be in the second quadrant because cosine is negative there, and the range of the inverse cosine function for negative values is from 0 to π.
Use Calculator for Computation: To find the principal value, we can use a calculator to compute cos−1(−0.26). Make sure the calculator is set to radian mode since the answers are given in radians.
Calculate Principal Value: Using a calculator, we find that cos−1(−0.26)≈1.83 radians.
Verify within Range: Since 1.83 radians is within the range of 0 to π, it is the principal value for cos−1(−0.26). Therefore, the correct answer is (D) 1.83.
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