1) Draw a line OA = 3 cm
2) From O draw ∠AOY = 90° and From A draw ∠OAX = 30° above the horizontal, such that OY and AX intersect each other at B.
3) From O draw ∠AOY' = 90° and From A draw ∠OAX' = 30° below the horizontal, such that OY' and AX' intersect each other at C.
ABC is required equilateral triangle.
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