Tangency, Continued
To draw a line
To draw a tangent to a circle through a point. follow this table:
tangent to a
circle through a
point
Step
Action
1
Given a circle with the intended point of tangency at P, move a
triangle to a position where one side passes through the center of
the circle and point P.
2
Slide the triangle across the straightedge until the opposite side of
the triangle touches the circumference at P.
If P is outside of the circle, place the triangle with one straight side
passing from P to the circumference of the circle. Move the
triangle over so that the opposing straight side passes through the
center of the circle and intersects the circumference of the circle.
Mark this T for point of tangency. Return the triangle to the first
position.
2
Draw the required tangent.
Figure 2-27 shows the process for drawing a line tangent to a circle through a
given point.
Figure 2-27.—A line tangent to a
circle.
Continued on next page
2-28
