21 Test file number 73

  21.1 Problem number 265
  21.2 Problem number 275
  21.3 Problem number 286
  21.4 Problem number 782
  21.5 Problem number 795

Test folder name:

test_cases/4_Trig_functions/4.1_Sine/73_4.1.2.1-a+b_sin-^m-c+d_sin-^n