Trig Modelling

Hi

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Originally Posted by Webby

A mass on a spring moves up and down with its displacement given by;
x=3-4cos((2pi/5)t). X is in centimetres and t is in seconds.

a)find the inital displacement

This is $x(0)=3-4\cos\left(\frac{2\pi}{5}\cdot 0\right)= ?$

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b)the displacement after 30 seconds

This is $x(30)=3-4\cos\left(\frac{2\pi}{5}\cdot 30\right)= ?$

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c)the greatest displacement

Find the maximum of $x(t)$ using its derivative or the properties of the cosine function.