Concept:
The triangle inequality is one of the fundamental properties of normed spaces.
In an inner product space, the norm is defined by
\[
\|\alpha\|=\sqrt{(\alpha,\alpha)}
\]
For any two vectors \(\alpha,\beta\in V\),
\[
\|\alpha+\beta\|\leq \|\alpha\|+\|\beta\|
\]
Step 1: Understand geometrical meaning.
The expression
\[
\|\alpha+\beta\|
\]
represents the length of the sum of two vectors.
The triangle inequality says that the length of one side of a triangle cannot exceed the sum of the lengths of the other two sides.
Step 2: Write the standard result.
\[
\|\alpha+\beta\|\leq \|\alpha\|+\|\beta\|
\]
Step 3: Final answer.
\[
\boxed{\|\alpha+\beta\|\leq \|\alpha\|+\|\beta\|}
\]