Tangency, Continued
To draw an arc
tangent to two
lines at right
angles
It is impractical to draw small radii arcs by tangency construction. For small
radii or radii up to 5/8ths inch, draw a 45° bisector of the angle and locate
the arc by trial and error. You may also use a circle template so long as the
diameter of the circle precisely equals twice the required radius.
To draw an arc tangent to two lines at right angles. follow this table:
Step
Action
1
Given two lines at right angles to each other, strike an arc at a
selected radius intersecting the lines at tangent points T.
2
With the same selected radius and using points T as centers, strike
another arc to intersect at a point C.
3
With C as a center, use the selected radius to draw the required
tangent arc.
Figure 2-29 shows the process for drawing an arc tangent to two lines at right
angles.
Figure 2-29.—Drawing an arc tangent to a right angle.
Continued on next page
2-30
