SOLUTION:
Step 1 :
In this question,
we are given that the Cartesian equation, y = 4,
is equivalent to the polar equation .........
Step 2 :
Recall that:
[tex]\begin{gathered} y\text{ = r sin}\theta\text{ } \\ \text{Then, we are given that:} \\ \text{y = 4, then we have that:} \\ 4\text{ = r sin }\theta \\ \text{Then,} \\ r\text{ = }\frac{4}{\sin \text{ }\theta} \end{gathered}[/tex]CONCLUSION:
The final answer is:
[tex]\text{r = }\frac{4}{\sin \text{ }\theta}[/tex]