To determine the tension in the string number 1, we need additional information about the system or the specific setup involving the masses m1 and m2. The tension in a string depends on various factors such as the masses involved, the acceleration or forces acting on the system, and the angles at which the strings are inclined.
Please provide more context or details about the system or describe the forces and accelerations acting on the masses so that I can assist you in calculating the tension in string number 1.