A rotational sensor records that the cosine of an angle turned by a wheel is .

MATHEMATICS · Multi-part · AP · AP Precalculus · Trigonometric and Polar Functions · Trigonometric and Polar Functions

Problem

A rotational sensor records that the cosine of an angle turned by a wheel is 0.650.65. (i) Calculate the principal value α=arccos⁡(0.65)\alpha = \arccos(0.65) correct to three decimal places (radians). (ii) Convert α\alpha to degrees, correct to one decimal place. (iii) Within the interval 0≤θ≤2π0 \le \theta \le 2\pi, determine all values of θ\theta that satisfy cos⁡θ=0.65\cos\theta = 0.65. Give each value in radians correct to three decimal places and briefly justify your selections based on the symmetry of the cosine function and principal value considerations.

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