Find the pka through a titration curve.?

I titrated 25 mL NaOH (0.075M) with 10mL Acetic Acid (0.10M) + 40mL DI Water. I found that the Endpoints are at 13 ml where ph=6.09, and 14 ml where ph=10.55. I know I have to use pH=pKa+log(B/A).