Calculating Frequency and Voltage in Opamp Oscillator

[etf]

Hello.
Here is my task:

In oscillator circuit ideal opamps are used, it is known R=10K, C=10nF.
a) Calculate frequency of oscillations,
b) If Vcc=Vee=15V, calculate amplitude of voltages in points A, B and C.
a)
Here is my solution. I cut output loop, applied test generator and found loop gain on this way:

I cut loop on output, because they did same in this type of exercises. Is it general rule that to find loop gain Abeta, we cut loop on output?
How to solve task b) ?

 

[NascentOxygen]

You can break into the loop at any point; it's a series arrangement Aβ so just choose wherever is convenient.

Determining amplitudes: assuming the circuit does oscillate, then where would you expect to find the greatest amplitude sinewave: point A, B, or C? Explain why you nominate that point.