問題文全文(内容文)：
$\displaystyle \sum_{i=1}^\infty\ \tan^{-1}\displaystyle \frac{1}{k^2+k+1}$を求めよ。
$\displaystyle \sum_{i=1}^\infty\ \tan^{-1}\displaystyle \frac{1}{k^2+k+1}$を求めよ。
単元：
Warning: usort() expects parameter 1 to be array, bool given in /home/kaiketsudb/kaiketsu-db.net/public_html/wp-content/themes/lightning-child-sample/single.php on line 102
Warning: Invalid argument supplied for foreach() in /home/kaiketsudb/kaiketsu-db.net/public_html/wp-content/themes/lightning-child-sample/single.php on line 103
Warning: usort() expects parameter 1 to be array, bool given in /home/kaiketsudb/kaiketsu-db.net/public_html/wp-content/themes/lightning-child-sample/single.php on line 102
Warning: Invalid argument supplied for foreach() in /home/kaiketsudb/kaiketsu-db.net/public_html/wp-content/themes/lightning-child-sample/single.php on line 103
指導講師：
ますただ
問題文全文(内容文)：
$\displaystyle \sum_{i=1}^\infty\ \tan^{-1}\displaystyle \frac{1}{k^2+k+1}$を求めよ。
$\displaystyle \sum_{i=1}^\infty\ \tan^{-1}\displaystyle \frac{1}{k^2+k+1}$を求めよ。
投稿日：2021.10.25