The displacement ddd of a mechanical oscillator is modeled by the equation d=0.9cos(1.5t)−4.0sin(1.5t)d = 0.9 \cos(1.5t) - 4.0 \sin(1.5t)d=0.9cos(1.5t)−4.0sin(1.5t) where ddd is measured in millimetres and ttt is time in seconds. To analyze the peak amplitude of the oscillation, the expression is rewritten in the form Rcos(1.5t+α)R \cos(1.5t + \alpha)Rcos(1.5t+α), where R>0R > 0R>0.
Find the value of RRR.
Circle the correct answer from the options below:
3.13.13.1 \qquad 4.054.054.05 \qquad 4.14.14.1 \qquad 4.94.94.9
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