Sketch a right triangle corresponding to the trigonometric function of the acute angle theta. Use...

Note that, ${\displaystyle \csc \theta =}$ $\frac{\text{Hypotenuse}}{\text{Opposide side}}$
So $\text{Hypotenuse}=21$ and $\text{Opposite side}=5$.
Use Pythagorean theorem to find adjacent side as follows.
Adjacent side ${\displaystyle =\sqrt{{21}^2-5^2}}$
${\displaystyle =\sqrt{441-25}}$
${\displaystyle =\sqrt{416}}$
Sketch a right triangle for given trigonometric function.

Find the other five trigonometric function as follows.
${\displaystyle \sin \theta =}$ $\frac{\text{Opposide side}}{\text{Hypotenuse}}$ ${\displaystyle =\frac{5}{21}}$
${\displaystyle \cos \theta =}$ $\frac{\text{Adjacent side}}{\text{Hypotenuse}}$ ${\displaystyle =\frac{\sqrt{416}}{21}}$
${\displaystyle \tan \theta =}$ $\frac{\text{Opposide side}}{\text{Adjacent side}}$ ${\displaystyle =\frac{5}{\sqrt{416}}}$
${\displaystyle \sec \theta =}$ $\frac{\text{Hypotenuse}}{\text{Adjacent side}}$ ${\displaystyle =\frac{21}{\sqrt{416}}}$
${\displaystyle \cot \theta =}$ $\frac{\text{Adjacent side}}{\text{Opposide side}}$ ${\displaystyle =\frac{\sqrt{416}}{5}}$