( ( ( Put ( the ( triangles side ) ) ) ( by side ) ) ( , ( you ( ( ( ca n't ) ( ( count ( congruent shapes ) ) twice ) ) . ) ) ) )
(ROOT (S (S (VP (VB Put) (NP (DT the) (JJ triangles) (NN side)) (PP (IN by) (NP (NN side))))) (, ,) (NP (PRP you)) (VP (MD ca) (RB n't) (VP (VB count) (NP (JJ congruent) (NNS shapes)) (ADVP (RB twice)))) (. .)))
Put the triangles side by side, you can't count congruent shapes twice.
(ROOT (S (NP (NP (DT The) (CD eight) (NNS sides)) (PP (IN of) (NP (DT an) (NN octahedra)))) (VP (VBP are) (PP (IN in) (NP (NP (DT the) (NN shape)) (PP (IN of) (NP (DT a) (NNS triangles)))))) (. .)))