Convert equation of circle in rectangular form to polar form

The video tutorial covers the concept of R Sine of Theta, starting with an introduction and initial steps. It then explains how to expand a binomial and perform mental calculations. The tutorial connects X^2 + Y^2 to R^2 without using a calculator, followed by steps to solve for R and simplify the equation. Finally, it discusses the final steps in solving and considerations about square roots.

What does the teacher expect students to do instead of using a calculator?

Why is it mentioned that you cannot take the square root of sine directly?