The measure of angle ACB for circle centered at point O is 21°
An equation is an expression that shows the relationship between two or more numbers and variables.
∠AOB = 2 * ∠ACB (angle at center is twice the angle at circumference)
42 = 2 * ∠ACB
∠ACB = 21°
The measure of angle ACB for circle centered at point O is 21°
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