61. Can the plane be "tiled": a) with triangles equal to a given one; b) with quadrilaterals equal to a given one?
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Official solution
61. It is not difficult to prove that the diagonals of this quadrilateral serve as the bisectors of its angles, and such a convex quadrilateral is a rhombus.
62. a) possible, c) possible.
Source: NuminaMath-1.5,
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