Kinematics of rigid rotor - angular acceleration

[dorratz]

Homework Statement

http://pho.to/A7jM2 [Broken]

Homework Equations

The Attempt at a Solution

My question is why the answer of question 15.258 (a) about the angular acceleration of rod BD isn't correct.
I used the realtion of tan(25) in the end of the solution.

 

[Simon Bridge]

Please explain your reasoning.

 

[dorratz]

Is my equations are ok and you are only asking about the final equation with tan(25) and the t component and the n component?