Every elliptical involution has the property that there are two definite points in the plane from which…
To find the angle between two given lines a, b of which the projections a1, b1 and a2, b2 are given.
The straight line is the simplest type of locus and the simplest first degree equation.
The lines of contact are equal, but the axes are neither parallel to each other, or the line of contact.
Circles should be unshaded or shaded evenly with thick and thin lines, changing at about 45 degrees.