题目2A. 30°B. <img src="https://tihai-oss-cloud.itihey.com/img/648ada05b7f36e55534860d1c9d71b0b.png">C. <img src="https://tihai-oss-cloud.itihey.com/img/bb57778f5f1e389a0686a9554df5fb35.png">D. <img src="https://tihai-oss-cloud.itihey.com/img/e3ad888690eb0915c5c7b210fbd89b5d.png">rad