Point О is the center of the circle, ∠AOB = 84 °. Find the value of the angle ACB

By the condition ∠AOB = 84 °, this angle is central, respectively, the arc AB (lower part) is also equal to 84 °. ∠ACB – is an inscribed angle and is equal to half of the arc on which it relies (by the inscribed angle theorem). Accordingly, 84/2 = 42.
Answer: 42

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