need to understand this 2, explanation please

The polar coordinates of a point are given. Find the rectangular coordinates of this point. What are the rectangular coordinates of this point? (Type an ordered pair. Type an exact answer, using radicals as needed Use integers or fractions for any numbers in the expression. Rationalize all denominators. Simplify your answer!) Find any of the values a, , d, an, n, or S,, that are missing from the arithmetic sequence 20 3 1= 20, $20 3 The value of azo is . (Simplify your answer Type an integer or a fraction.) The value of d is (Simplify your answer. Type an integer or a fraction.)