In a right triangle, angle $J$ has opposite side length $20$ and adjacent side length $21$. What is the value of $\sin J$?

Given that a transversal cuts two parallel lines and forms angles such that $m\angle 4$ = $55.1°$, what are the measures of $m\angle 5$ and $m\angle 7$?

Given a right triangle where angle $A$ measures $39°$ and side $\mathrm{BC}$ is the hypotenuse, what is the measure of arc $\mathrm{BC}$ in degrees?

Given a right triangle with hypotenuse of length $c$ and an acute angle $\theta$, express the lengths of the side adjacent to $\theta$ (labeled $a$) and the side opposite $\theta$ (labeled $b$) in terms of $c$ and $\theta$.

Given a right triangle where one of the acute angles is $\theta$, and the side opposite $\theta$ has length $3$, the side adjacent to $\theta$ has length $4$, and the hypotenuse has length $5$, what are the exact values of the six trigonometric ratios for angle $\theta$?