If the tangent line at a point (x, y) on the curve y = f(x) is parallel to y-axis, find the value of

Write the value of if the normal to the curve y = f(x) at (x, y) is parallel to y-axis.

If the tangent to a curve at a point (x, y) is equally inclined to the coordinate axes, then write the value of

Find the slope of the normal at the point ‘t’ on the curve

Write the coordinates of the point on the curve y² = x where the tangent line makes an angle with x-axis.