Question 8: Circle Theorem

    Angles subtended by the same arc in the same segment are equal.  
    Arc AC subtends $\angle ADC$ and $\angle ABC$.  
    Therefore, $\angle ABC = \angle ADC = 35^\circ$.

    Since AB is the diameter, $\angle ACB$ is an angle in a semicircle.  
    Therefore, $\angle ACB = 90^\circ$.