Unit Vectors

Step 1: Find the direction vectors of lines AB and CD:

Step 2: Use the dot product formula to find the cosine of the angle between the two vectors: First, compute the dot product: Now, compute the magnitudes of and :

Step 3: Substitute the values into the formula for : Thus, the angle between the lines is .

Step 1: Find the magnitude of each vector:

Step 2: Apply the Pythagorean theorem to check if the sum of squares of two vectors equals the square of the third vector.

Step 3: If the equation holds, the vectors form a right-angled triangle.