(ii) Successive bisection of chord

In this method, points on a curve are located by bisecting the chords and
the perpendiculars at the mid-point.
Referring to Fig. 2.7

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Fig. 2.7

Perpendicular offset at middle of long chord (72) is

CD = ‏م -م‎ cos = = R(1-—cos >}

Let ‏رط‎ be the middle of 72. Then Perpendicular offset

)4 81-00 = رص

Similarty, ೧,೬ #(1-०० है)
Using symmetry points on either side may be set.

(iii) Offsets from the tangents—perpendicular or radial