题目已知⊙O\odot O⊙O的半径为222,△ABC\triangle ABC△ABC内接于⊙O\odot O⊙O,AB=2AB=2AB=2,则∠ACB=______.\angle ACB=\_\_\_\_\_\_.∠ACB=______.知识点：圆周角定理I章节：第28章 圆 / 28.3 圆心角和圆周角
