cos(n)pi = (-1)^n

Math Central

Quandaries & Queries

Subject: mathematical induction
Name: Idrees (tararid@yahoo.com)
Who are you: Student

How can I prove the following:
cos(n)pi = (-1)^n

Hi Idrees.

If you start by showing that cos(0) = -cos(0+pi), then you can use induction to prove the rest.

Stephen La Rocque.>

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