Q:   Add these two equations together, then solve for the
             radius R<sub>A</sub>.


                 4 RA   =   [ (t4 - t1) + (t3 - t2) ] * (v1 + v2)

                   RA   =  0.25 *  [ (t4 - t1) + (t3 - t2) ] * (v1 + v2)



       Then plug in values to compute the radius of star A in meters.


             RA   =  0.25 *  [ (17300 s) + (6050 s) ] * (150 km/s)

                  =   8.76 x 10^(8) m

                  =   1.26  solar radii