1. What is the gradient of a vertical line?

The gradient of a vertical line is undefined. This is because the denominator of the gradient fraction i.e. the change in x, would be zero and division by zero is impossible in mathematics.

2. Is it also not possible to find the gradient of a horizontal line?

The gradient of a horizontal line is ZERO.

3. What angle is a line with a gradient of 1?

A line with a gradient of 1 makes an angle of 45° with the horizontal.