How do you find the period of #y= -4 cos 2x#?

1 Answer
Sudip Sinha
Jul 28, 2015

#pi#

Explanation:

Let us look at a more general problem: #f(x) = A cos(nx)#. In this case, we have # f(x + 2pi/n) = A cos(n(x + 2pi/n)) = A cos(nx + 2pi) = A cos(nx) #. Try this also for #sin#; it is exactly the same.

Thus we see that the period of such a general function is # (2pi)/n #.

Therefore for #f(x) = -4 cos(2x)#, the period is # (2pi)/n = (cancel2 pi)/cancel2 = pi #.

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