MathDB

Let

t_1,t_2,\ldots,t_k

be different straight lines in space, where

k>1

. Prove that points

P_i

t_i

i=1,\ldots,k

, exist such that

P_{i+1}

is the projection of

P_i

t_{i+1}

for

i=1,\ldots,k-1

, and

P_1

is the projection of

P_k

t_1

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