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The Cosmic Triangle} represents the three key

cosmological parameters -- $\Omega_m$, $\Omega_{\Lambda}$, and $\Omega_k$ -- where each point in the triangle satisfies the sum rule $\Omega_m + \Omega_{\Lambda} + \Omega_k = 1$. The blue horizontal line (marked Flat) corresponds to a flat universe ($\Omega_m + \Omega_{\Lambda} = 1$), separating an open universe from a closed one. The red line, nearly along the $\Lambda=0$ line, separates a universe that will expand forever (approximately $\Omega_{\Lambda}>0$) from one that will eventually recollapse (approximately $\Omega_{\Lambda}<0$). And the yellow, nearly vertical line separates a universe with an expansion rate that is currently decelerating from one that is accelerating. The location of three key models are highlighted: (flat) standard cold-dark-matter ({\sc Scdm}) ; flat ($\Lambda${\sc cdm}); and Open CDM ({\sc Ocdm}),. The right panel schematically shows the complementarity of constraints ($\sim 1\sigma$) from LSS, High-z SN Ia, and CMB anisotropy are shown by the three color bands.The three independent bands intersect at the emergent concordance model -- flat model with $\Omega_m\sim 0.3$ and $\Omega_{\Lambda}= 0.7$ .