If $\sin \alpha = 3/5, \cos \beta = 12/13$, what's $\cos(\alpha + \beta)$?

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Given that \(\sin \alpha = \dfrac{3}{5}\) and \(\cos \beta = \dfrac{12}{13}\), prove that one possible value of \(\cos(\alpha + \beta)\) is \(\dfrac{33}{65}\)…

Could we draw a diagram with right-angle triangles and the angles \(\alpha\), \(\beta\) and \(\alpha+\beta\)?

If two sides of a right-angle triangle are \(3\) and \(5\), what is the third side?