Massless particle revolving in a circle

[iNCREDiBLE]

Given: A massless particle revolving in a circle with a rotational velocity = (2+sin(a))
To Find: Y-axis acceleration
Method #1 (from rotational acceleration)
Y-axis acceleration = (2+sin(a))(cos(a))^2
Method #2 (from Y-axis velocity)
Y-axis acceleration = (2+sin(a))(cos(a))^2-(sin(a))(2+sin(a))

Which Y-axis acceleration is correct and why?

Can someone explain this?

 

[HallsofIvy]

rotational velocity = (2+sin(a))

What does this mean? Is a an angle? If so what angle?
And what do you mean by "y-axis" acceleration? Are we to assume that the circle is in the xy-plane and you are looking for the y-component of acceleration?

 

[iNCREDiBLE]

What does this mean? Is a an angle? If so what angle?
And what do you mean by "y-axis" acceleration? Are we to assume that the circle is in the xy-plane and you are looking for the y-component of acceleration?

You tell me. I have no clue what they are asking.

 

[Gokul43201]

Post the problem EXACTLY as it appears in your text/homework. Attach any pictures that come with the problem (or describe them).