题目

What dress size does the woman want?A．8.B．10.C．12. 答案：【答案】C【解析】【原文】M: Can I help you?W: I'm looking for a size twelve dress. M: Oh, let me see. An eight, a ten. Ah, you're lucky. I have the prettiest dress here in a twelve. Why don't you try it on?如图，在△ABC中，AD⊥BC，垂足为D．若AB=10，AD=7，CD=2． (1)求cosB，sinC的值； (2)求tanB．tan∠BAD，tan∠CAD的值．