A3. Segment $AB$ is 20 cm long. The broken line connecting points $A$ and $B$ forms 7 equilateral triangles with segment $AB$. No segment of the broken line lies on segment $AB$. How many centimeters is the broken line long?

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(A) $40 \sqrt{3}$
(B) 40
(C) $20+20 \sqrt{3}$
(D) $20+20 \sqrt{2}$
(E) It is impossible to determine.
A3. Let's denote the lengths of the sides of these 7 equilateral triangles in sequence by $a_{1}, a_{2}, \ldots, a_{7}$. The length of the segment $A B$ is then $a_{1}+a_{2}+\ldots+a_{7}$, and the length of the broken line from $A$ to $B$ is $2 a_{1}+2 a_{2}+\ldots+2 a_{7}=2\left(a_{1}+a_{2}+\ldots+a_{7}\right)$. The length of the broken line is thus twice the length of the segment and is therefore equal to $40 \mathrm{~cm}$.