Prove that 1,1,1 cannot be direction cosines of a straight line.

Explanation

To prove that \(1, 1, 1\) cannot be direction cosines of a straight line, we will follow these steps:

### Step 1: Understanding Direction Cosines
Direction cosines of a straight line are defined as the cosines of the angles that the line makes with the coordinate axes. If a line has direction cosines \(L\), \(M\), and \(N\), then they must satisfy the equation:

\[ L^2 + M^2 + N^2 = 1 \]
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