Sheet is folded in marked format and cut led at last as shown. Identify from the options below, how the pattern will be made when it is fully unfolded?
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Unfolding reverses the folds: the cut triangle and dot are reflected about the diagonal and about the two middle lines, giving eight copies.
Folds: the top half is folded down along the horizontal middle line, then the right half is folded onto the left half along the vertical middle line, and finally the lower-right half of the small square is folded along the diagonal onto the upper-left half. The cut is made in the last small right-angled triangle, whose right-angle corner is on the left edge of the original sheet at the middle of that edge. The cut consists of a small black right triangle near the right-angle corner (right angle at its upper left) and a round hole a little further inside. Unfolding: reflect the cut across the diagonal, then across the vertical middle line, then across the horizontal middle line. This gives 8 triangles and 8 holes arranged symmetrically about the centre. Triangles at the left edge: above the middle line the right angle is at the lower left, below the middle line it is at the upper left. Triangles at the right edge: above the middle line the right angle is at the lower right, below it at the upper right. At the top edge: left triangle has its right angle at the upper right, right triangle at the upper left. At the bottom edge: left triangle has its right angle at the lower right, right triangle at the lower left. The holes lie in the eight symmetric positions beside these triangles. Figure B is the only figure in which all eight triangles have these orientations (figures A, C and D each have two or more triangles turned the wrong way on the left and right sides). In the paper the answer options are listed as 1 = B, 2 = A, 3 = D, 4 = C, so the correct choice is option (1), figure B. Answer: (1) B
