53 Test file number 89

  53.1 Problem number 792
  53.2 Problem number 852
  53.3 Problem number 853
  53.4 Problem number 867
  53.5 Problem number 875

Test folder name:

test_cases/4_Trig_functions/4.2_Cosine/89_4.2.2.1-a+b_cos-^m-c+d_cos-^n