曲线<img src="https://storage.tutusouti.com/pzst/question_bank/res/bd/51/bd51b3bc520c68d281a9b3c363f205f949a42a88.jpg?x-oss-process=image/sharpen,200"/>在<img src="https://storage.tutusouti.com/pzst/question_bank/res/bb/0b/bb0b331263762abcb22367486aa8db38c7861698.jpg?x-oss-process=image/sharpen,200"/>处的切向量是（）