To calculate the segment AB you have to use the following formula
[tex]AB=\text{ }\frac{\theta}{180º}\pi R[/tex]
θ represents the central angle θ =90º
R represents the radius R= 7.9cm
[tex]AB=\frac{90}{180}\cdot314\cdot7.9=\text{12.403cm}[/tex]
The length of segment AB= 12.403cm
