Penguins and Mixing Dependent CP Violation

Constraints on angles of Unitarity triangle are reviewed, and in particular constraint on $\gamma$ from limit on $\Delta m_s$ is emphasized. Effects of penguin diagram on measurement of $\beta$ and $\alpha$ are then reviewed. New measurements on $B \to \pi^+\pi^-$ in QCD improved factorization approximation suggest large penguin effects. It is possible to estimate the error in measurement of $\alpha$ as a function of $\gamma$ for different $|V_{ub} /V_{cb}|$ values.