Given $x=\sin \frac{\pi }{2}$ and $y=\cos \frac{\pi }{2}$, which of the following is correct for $x$ and $y$ where $0\le \theta \le \pi$?

The radius of the unit circle intersects the circle at the point where the angle is $\frac{\pi }{4}$ radians. What is the approximate value of $y$ at this point?

On the unit circle, what is the radian measure of the arc that subtends a central angle of $90°$?

Which of the following expressions is equivalent to $\sin (22°)$?

On the unit circle, for $0<\theta <\pi$, when is $tan\left(\theta \right)$ undefined?

Given the polar equation $r^2=\sin \left(2\theta \right)$, which of the following best describes the shape of its graph on the unit circle?

Write the complex exponential function $e^{i\theta }$ as a sum of its real and imaginary parts:

Given the sequence defined by $a_n=\cos \left(n\pi \right)$, which of the following lists the first five terms of the sequence?