—Yes, it's ____ pen

为更好落实《国家学生体质健康标准》，宜宾市教育部门将中长跑、立定跳远、坐位体前屈作为中考测试题目，测试中我们需要依赖一定的身体结构才能完成系列运动，如图分别是伸肘动作产生的示意图和关节模式图，据图回答：

Protect Wild Animals

    Animals are our good friends．We live in the same Earth．Animals and people can't  be separated from each other．But some animals are getting less and less．So it's important to us to protect animals，especially wild animals．Some people kill wild animals because of money．It's wrong．Now people need more places to live in．We explore the forest．  Animals have less places to live in．The number of wild animals decreases year by year．So we should protect wild animals．

已知0＜α＜β＜$\frac{\mathrm{\pi }}{2}$，且cosαcosβ+sinαsinβ=$\frac{4}{5}$，tanβ=$\frac{4}{3}$，则tanα=____