As shown in the figure, it is known that ∠ AOB = 90 °, EOF = 60 °, OE bisects ∠ AOB, of bisects ∠ BOC, and the degrees of ∠ AOC and ∠ cob are calculated

∵ OE bisection ∠ AOB, of bisection ∠ BOC, ∵ BOF = 12 ∠ AOB = 12 × 90 ° = 45 °, ∵ BOF = ∠ BOF = 12 ∠ BOC, ∵ BOF = ∠ EOF - ∠ BOE = 60 ° - 45 ° = 15 °, ∵ BOC = 2 ∠ BOF = 30 °, ∵ AOC = ∠ BOC + ∠ AOB = 30 ° + 90 ° = 120 °

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