S. How to Construct an Arc Tangent to Two Radii or
Diameters
Given: Diameter A and arc B with center points located, and
the required radius.
Step 1: Set the compass at the required radius and, out of the
way, swing a radius of the required length from a
point on the circumference of given diameter A. Out of
the way, swing a required radius from a point on the
circumference of a given arc B.
Step 2: From the extreme high points of each radius,
construct a light radius out side of the given radii A
and B.
Step 3: Where these arcs intersect is the exact location of the
required swing point. Set the compass point on the
swing point and lightly construct the required radius.
Allow the radius swing to extend past the required
area.
Step 4: Check all work; darken in the radii using the correct
line thickness. Darken in the arcs or radii in
consecutive order from left to right or from right to left,
thus constructing a smooth connecting line having no
apparent change in direction.