Non uniform circular motion of a disc

[dsimpson]

Homework Statement

When powered up, a disk drive starts at rest and spins up with non-uniform acceleration. this lasts for 1.66 seconds after which it does not accelerate any more. how fast is it spinning at .87 seconds?
alpha(i)=605 rad/s^2
B=1.89
Radius=2.03 cm

Homework Equations

alpha=alpha(i)sin(Bt)

The Attempt at a Solution

i don't know how to relate the tangential acceleration into my velocity. I know that At^2=Ar^2+At^2 and At^2=v^2/r, but i can't finish this. please help!

 

[Astronuc]

See examples here.

http://hyperphysics.phy-astr.gsu.edu/hbase/rotq.html#drot

One has a time-dependent angular acceleration over time, and one wishes to find the angular velocity at a given time.

The key is to relate angular velocity ω(t) to angular acceleration α(t) knowing that α(t) = dω(t)/dt.

Much like http://hyperphysics.phy-astr.gsu.edu/hbase/acons.html#c2

 

[dsimpson]

so if i understand you correctly, i just need to integrate to achieve my answer?