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Trigonometry and Modelling

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Question 10

A robotic arm rotates such that its displacement angle α\alphaα in radians satisfies the drive torque equation:

3sin⁡α(4cot⁡22α−5)=8sec⁡α 3 \sin \alpha (4 \cot^2 2\alpha - 5) = 8 \sec \alpha 3sinα(4cot22α−5)=8secα
a.

Show that this equation can be expressed in the form

12csc⁡22α−16csc⁡2α−27=0 12 \csc^2 2\alpha - 16 \csc 2\alpha - 27 = 0 12csc22α−16csc2α−27=0
[4]
b.

Hence, for 0<α<π20 < \alpha < \frac{\pi}{2}0<α<2π​, determine the possible values of the displacement angle α\alphaα, giving your answers to 3 significant figures.

[5]

Trigonometry and Modelling Questions

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