Respuesta :

Answer:

107.2

Step-by-step explanation:

  1. cosK= (81^2)+(20^2)-(89^2) / 2(81)(20)
  2. cosK= -960 / 3,240
  3. cosK= -02963
  4. K= cos^-1(0.9230)
  5. K=107.2