Two slides have different angles, find the numeric angle

[mikefitz]

In a playground, two slides have different angles of incline theta1 and theta2 (theta2 > theta1). A child slides down the first at constant speed; on the second, his acceleration down the slide is a. Assume the coefficient of kinetic friction is the same for both slides. (a) Find a in terms of
theta1, theta2, and g. (b) Find the numerical value of a for theta1 = 45° and theta2 = 61°.


I hate to post and run, but my trig skills are HORRIBLY lacking in this arena. Can any of you offer tips for solving (a)? thanks

 

[6Stang7]

since the first angle, theta1, resulted in no acceleration, what do we know about the forces involved?