阅读材料，回答问题

材料一：唐朝是个繁荣开放的朝代，与很多国家都有友好往来，特别是与日本和印度。通过频繁的交往，对两个国家产生了深远的影响。

材料二：唐朝时期实行开明的民族政策，注重与周边少数民族的友好往来，特别是对吐蕃，被尊称为“天可汗”。

材料三：“夫以铜为镜，可以正衣冠；以古为镜，可以知兴亡；以人为镜，可以明得失……”

材料四：见下图

比较大小： $1$ ____ $\sqrt{3}-1$ （填“﹤”，“＝”，“﹥”）.

    During holidays，Kitty usually goes to see the exhibits in many museums，such as the history museum，the art museum，the museum of science and technology and the museum of natural history．There are thousands of wonderful things in museum.There are paintings，sculptures(雕塑)，costumes(服饰)，swords(剑)，ancient animal bones and plants，stuffed animals(动物标本)and many others．It is always a good review of history to visit those museums．It is also a great way to learn more things by myself．

已知向量$\overrightarrow{a}$，$\overrightarrow{b}$的夹角为60°，且|$\overrightarrow{a}$|=2，|$\overrightarrow{b}$|=1，若$\overrightarrow{c}$=$\overrightarrow{a}$﹣4$\overrightarrow{b}$，$\overrightarrow{d}$=$\overrightarrow{a}$+2$\overrightarrow{b}$，求

（1）$\overrightarrow{a}$•$\overrightarrow{b}$；                 

（2）|$\overrightarrow{c}$+$\overrightarrow{d}$|．