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?

Math Tricks To Remember The Unit Circle (video lessons, examples and solutions)

Unit Circle Tangent, Definition, Values & Examples - Lesson

algebra precalculus - A few questions regarding the cosine difference identity - Mathematics Stack Exchange

Solved Use the unit circle (and algebra) to solve each

Solved Use the unit circle to find all of the exact value(s)

5.2: Unit Circle - Sine and Cosine Functions - Mathematics LibreTexts

Unit Circle - Trigonometry

Evaluate the following expression by drawing the unit circle and the appropriate right triangle. The angle is in radians. c o s ( 5 pi 3 )

algebra precalculus - Why is using the arc length of a circle, $s$, equivalent to using the angle measure in radians, $ heta$, as the input of the trigonometric functions? - Mathematics Stack Exchange