题目

Can you understand the beginning of this essay? “My smmr hols wr CWOT．B4．we usd 2go2 NY 2C my bro, his GF & 3 kds FTF.”     The Scottish teacher who received it in class had no idea what the girl who wrote it meant． The essay was written in a form of English used in cell phone text messages．Text messages(also called SMS)through cell phones became very popular in the late 1990s．At first mobile phone companies thought that text messaging would be a good way to send messages to customers，but customers quickly began to use the text messaging service to send messages to each 在直角坐标系中，已知A（3，0），B（0，3），C（cosθ，sinθ）．（1）若θ锐角，且sinθ=，求•；（2）若⊥，求sin2θ．