Answer :
By the cosine rule
430^2 = 260^2 + 480^2 - 2(260)(480)cos(C)
C = arccos([260^2 + 480^2 - 430^2]/2(260)(480)
C = 63.1 degrees (nearest tenth of a degree)
430^2 = 260^2 + 480^2 - 2(260)(480)cos(C)
C = arccos([260^2 + 480^2 - 430^2]/2(260)(480)
C = 63.1 degrees (nearest tenth of a degree)