For a cosine function with amplitude A=0.75 and period T=10, what is y(4)?

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I keep getting 0.749...help is appreciated :)

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Answer 1 · 2018-07-02T18:59:47

#-0.6067627457812105#

The cosine function with amplitude #0.75#

#y=0.75\cos(kx)#

But period of above cosine function is #10#

#\therefore {2\pi}/k=10#

#k=\pi/5#

Thus, the function is #y=0.75\cos({\pi x}/5)#

#\therefore y(4)=0.75\cos({4\pi}/5)#

#y(4)=-0.6067627457812105#