Prove that points `hati+2hatj-3hatk, 2hati-hatj+hatk and 2hati+5hatj-hatk` form a triangle in space.

Explanation

To prove that the points \( A = \hat{i} + 2\hat{j} - 3\hat{k} \), \( B = 2\hat{i} - \hat{j} + \hat{k} \), and \( C = 2\hat{i} + 5\hat{j} - \hat{k} \) form a triangle in space, we will follow these steps:

### Step 1: Define the points
Let:
- Point \( A \) be represented as \( A(1, 2, -3) \)
- Point \( B \) be represented as \( B(2, -1, 1) \)
- Point \( C \) be represented as \( C(2, 5, -1) \)

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