The graphs of polar equations in the forms r = a(cos + 1), r = a(cos

Question:

The graphs of polar equations in the forms r = a(cos θ + 1), r = a(cos θ - 1), r = a(sin θ + 1), and r = a(sin θ - 1) are called cardioids because they resemble hearts. Graph several curves in the cardioids family. Generalize your results by answering the questions.
a. How do the graphs of r = a(cos θ + 1) and r = a(cos θ - 1) differ?
b. How do the cardioids created with sine differ from those created with cosine?
c. What is the effect of the coefficient a?