algebra precalculus - Using unit circle to explain $\cos(0) = 1

We have been taught $\cos(0) = 1$ and $\sin(90) = 1$. But, how do I visualize these angles on the unit circle?

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cos0, SAVE 56%

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PPT - The Unit Circle PowerPoint Presentation, free download - ID:2184628

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Trigonometry - Easy Way To Memorize The Unit Circle