( However ( , ( ( the ( two rays ) ) ( ( are ( displaced ( by ( ( ( a ( lateral distance ) ) , ) d ) ) ) ) . ) ) ) )
(ROOT (S (ADVP (RB However)) (, ,) (NP (DT the) (CD two) (NNS rays)) (VP (VBP are) (VP (VBN displaced) (PP (IN by) (NP (NP (DT a) (JJ lateral) (NN distance)) (, ,) (NP (SYM d)))))) (. .)))
However, the two rays are displaced by a lateral distance, d .
(ROOT (S (NP (NNP Distance)) (VP (VBZ is) (VP (VBN defined) (PP (IN as) (NP (NP (DT the) (NN magnitude) (CC or) (NN size)) (PP (IN of) (NP (NP (NN displacement)) (PP (IN between) (NP (CD two) (NNS positions))))))))) (. .)))