Answer
Fill the blanks with
... y ... r ...
... x ... r ...
... y ... x ....
Work Step by Step
Book reference: Figure2, Definition, page 491.
For P(x,y) as described in the problem text,
$\displaystyle \sin\theta=\frac{y}{r},\quad\cos\theta=\frac{x}{r},\quad\tan\theta=\frac{y}{x}, x\neq 0$
Fill the blanks with
... y ... r ...
... x ... r ...
... y ... x ....
