How the last prob. Can be solved when u put y=acos(theta) ?. Actually, y=asin(theta) so how y can be acos(theta)?####[['y', 'Mathematical_Related_Concept', 'NEG'], ['acos(theta)', 'Mathematical_Related_Concept', 'NEG'], ['y=acos(theta)', 'Mathematical_Related_Concept', 'NEG'], ['y=asin(theta)', 'Mathematical_Related_Concept', 'NEG']]