题库网
#8d15f7b5-34e0-4524-bb02-b000c32ef0e1基础填空题等差数列的概念与通项数列

2. 已知数列{an}\{a_{n}\}是等差数列,且a2+a5+a8=πa_{2}+a_{5}+a_{8}=\pi,则tan(a1+a9)=(\tan (a_{1}+a_{9})=(  ))