How to Find the Coefficients For the Chebyshev Expansion of a Function

Question

Find and building a Fourier series of a function $f(x)$ on an arbitrary interval $[a,b]$ is explained here. I know that for Chebyshev series, the expansion is $$f(x) \sim \sum_{i=0}^{N} c_i T_i(x)$$ as $N \to \infty$. However, how would you find each $c_i$, specifically for $f$ on $[a,b]$?