Expression 9: Start integral from "a" Subscript, "s" "t" "a" "r" "t" , Baseline to "b" Subscript, "f" "i" "n" "i" "s" "h" , Baseline , end integral, StartRoot, left parenthesis, "f" prime left parenthesis, "t" , right parenthesis , right parenthesis squared plus left parenthesis, "g" prime left parenthesis, "t" , right parenthesis , right parenthesis squared , EndRoot "d" "t"∫bfinishastartf′t2+g′t2dt