  The unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix has been well
established by both direct and indirect measurements without any evidence of
discrepancy. The CKM weak phase $\alpha$ is directly measured using an isospin
analysis in $B\rightarrow \pi\pi$ and $B\to \rho\rho$ assuming that electroweak
penguin contributions are ignorable. However, electroweak penguins are
sensitive to NP, hence, it is important to experimentally estimate their
effects. We determine the size of both electroweak penguin and isospin
amplitudes, directly from $B\rightarrow \pi\pi$ and $B\to \rho\rho$
experimental data, using in addition the indirectly measured value of $\alpha$.
We find that electroweak penguin contribution are indeed small and agree with
SM expectations within $1\sigma$. We also find that there is a mild enhancement
of the $\Delta I=\tfrac{1}{2}$ transition amplitude.
