4. In a lemniscate curve the ratio of the angle between the tangent at the end of the polar ray and the straight, and the angle between the polar ray and the straight, is
9. To set out a parallel from a given inccessible point to a given line AB, the following observations and made Distance AB and angle PAM = a and angle PBA = b are measured where Mis a point on the line BA produced. The perpendicular to the desired parallel line from A and B are :