Integrate cos(pi x) from x = 0 to 7 using an appropriate substitution

Those last problems were a bit tough. Here's a simpler definite integral as a confidence booster!
Integrate cos(pi x) from x = 0 to 7 using an appropriate substitution
Integrate cos(pi x) from x = 0 to 7 using an appropriate substitution
Integrate cos(pi x) from x = 0 to 7 using an appropriate substitution

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