Question 120
let $\alpha, \beta, \gamma$ be the angles in triangle $\Delta$. SUPPOSE THAT $\sin \alpha \gt \cos \beta$, $\sin \beta \gt \cos \gamma$, and $\sin \gamma \gt \cos \alpha$. prove that $\Delta$ is acute-agled. The angles of the triangle $\alpha, \beta, \gamma$ satisfy the inequalities $\sin \alpha \gt \cos \beta, \sin \beta \gt \cos \gamma, \sin \gamma \gt \cos \alpha$. Prove that the triangle is acute.