Circular motion of a train magnitude and angle

[tyro008]

Homework Statement

A train is rounding a circular curve whose radius is 2.00 X 10_{}2 m. At one instant, the train has an angular acceleration of 1.50 X 10^-3 rad/s_{}2 and an angular speed of 0.0400 rad/s.
(a) Find the magnitude of the total acceleration (centripetal plus tangential) of the train.

(b) Determine the angle of the total acceleration relative to the radial direction.

Homework Equations

a_{}NET = \sqrt{}ac2^{}_{} + at2^{}
and Ac is the centripetal acceleration, At is the tangential acceleration

The Attempt at a Solution

i tried using this equation, but i couldn't find At. to find this, you need delta velocity divided by delta time, but there is no time and i don't know if angular speed is the same thing as regular velocity

 

[grassblade]

You can find At by using the formula: angular acceleration = tangential acceleration / radius.

I'm not sure how to find the angle though...