Expressão 4: left parenthesis, StartFraction, "x" Subscript, 1 , Baseline cos left parenthesis, 45 "t" Subscript, 1 , Baseline , right parenthesis Over 2 , EndFraction , StartFraction, "y" Subscript, 1 , Baseline sin left parenthesis, 90 "t" Subscript, 1 , Baseline , right parenthesis Over 1 , EndFraction , right parenthesisx1cos45t12,y1sin90t11