Find the length of the vector AB, if a A (3; -6,), B (-4; -7).

The length of any vector on the plane can be found using the coordinates of its beginning and end using the following formula: | AB | = √ ((x2 – x1) ^ 2 * (y2 – y1) ^ 2), where x1, y1 are the coordinates of the beginning of the vector, and x2, y2 are the coordinates of the end.
Then the length of the original vector will be equal to √ ((- 4 –3) ^ 2 * (-7 + 6) ^ 2) = √ ((- 7) ^ 2 * (-1) ^ 2) = √ (49 * 1) = 7.
Answer: | AB | = 7.