( ( The ( tilt angle ) ) ( ( is ( ( that angle ) ( measured ( from ( the ( horizontal plane ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN tilt) (NN angle)) (VP (VBZ is) (NP (NP (DT that) (NN angle)) (VP (VBN measured) (PP (IN from) (NP (DT the) (JJ horizontal) (NN plane)))))) (. .)))
The tilt angle is that angle measured from the horizontal plane.
(ROOT (S (NP (NP (NNP Instruments)) (SBAR (WHNP (WDT that)) (S (VP (VB measure) (NP (NP (DT the) (NN angle)) (PP (IN of) (NP (NP (DT the) (NN slope)) (PP (IN of) (NP (DT a) (NN volcano)))))))))) (VP (VBP are) (VP (VBN called) (NP (NN tilt) (NNS meters)))) (. .)))