Three-centred spiral

Answer
Solution

1. Draw an equilateral triangle

2. Extrend its sides.

3. Using 1 as the centre and 1-3 as the radius, draw the arc 3-A.

4. Using 2 as the centre and 2-A as the radius, draw the arc A-B.

5. Using 3 as the centre and 3-B as the radius, draw the arc B-C.

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1

2

3

A

B

C

D

E