( ( In geometry ) ( , ( ( a lens ) ( ( is ( ( a ( biconvex ( ( -LRB- ( convex-convex -RRB- ) ) shape ) ) ) ( comprising ( ( ( two ( circular arcs ) ) , ) ( joined ( at ( their endpoints ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN In) (NP (NN geometry))) (, ,) (NP (DT a) (NN lens)) (VP (VBZ is) (NP (NP (DT a) (NN biconvex) (PRN (-LRB- -LRB-) (NP (NNP convex-convex)) (-RRB- -RRB-)) (NN shape)) (VP (VBG comprising) (NP (NP (CD two) (JJ circular) (NNS arcs)) (, ,) (VP (VBN joined) (PP (IN at) (NP (PRP$ their) (NNS endpoints)))))))) (. .)))
In geometry, a lens is a biconvex (convex-convex) shape comprising two circular arcs, joined at their endpoints.
(ROOT (S (NP (DT The) (ADJP (RBS most) (JJ common)) (JJ two-lens) (NN telescope)) (, ,) (PP (IN like) (NP (DT the) (JJ simple) (NN microscope))) (, ,) (VP (VBZ uses) (NP (NN convex) (NNS lenses))) (. .)))