\text { What is the Fourier transform of the function } 4 \cos (5 t) \text { on the interval }[-\pi, \pi] ? \text { a. } \cos (2 t)+\cos (4 t) b. none of the others c. 2 cos (t) +7 sin(2t) d. 4 cos(5t) 7 sin(2t) + 4 cos(5t)e.

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