Format improvement on equation

Author: jnonino

content/ai/math/algebra/vectors/index.en.md

@@ -218,15 +218,11 @@ $$
 Expanding the left side:
 
 $$
-\|\mathbf{u} - \mathbf{v}\|^2 = \|\mathbf{u}\|^2 + \|\mathbf{v}\|^2 - 2 \|\mathbf{u}\| \|\mathbf{v}\| \cos(\theta)
-$$
-
-$$
-(\mathbf{u} - \mathbf{v}) \cdot (\mathbf{u} - \mathbf{v}) = \|\mathbf{u}\|^2 + \|\mathbf{v}\|^2 - 2 \|\mathbf{u}\| \|\mathbf{v}\| \cos(\theta)
-$$
-
-$$
-\|\mathbf{u}\|^2 - 2 (\mathbf{u} \cdot \mathbf{v}) + \|\mathbf{v}\|^2 = \|\mathbf{u}\|^2 + \|\mathbf{v}\|^2 - 2 \|\mathbf{u}\| \|\mathbf{v}\| \cos(\theta)
+\begin{aligned}
+  \|\mathbf{u} - \mathbf{v}\|^2 = \|\mathbf{u}\|^2 + \|\mathbf{v}\|^2 - 2 \|\mathbf{u}\| \|\mathbf{v}\| \cos(\theta) \\
+  (\mathbf{u} - \mathbf{v}) \cdot (\mathbf{u} - \mathbf{v}) = \|\mathbf{u}\|^2 + \|\mathbf{v}\|^2 - 2 \|\mathbf{u}\| \|\mathbf{v}\| \cos(\theta) \\
+  \|\mathbf{u}\|^2 - 2 (\mathbf{u} \cdot \mathbf{v}) + \|\mathbf{v}\|^2 = \|\mathbf{u}\|^2 + \|\mathbf{v}\|^2 - 2 \|\mathbf{u}\| \|\mathbf{v}\| \cos(\theta)
+\end{aligned}
 $$
 
 Cancelling \(\|\mathbf{u}\|^2\) and \(\|\mathbf{v}\|^2\) from both sides: