某校七（3）班为了加强对学生青春期的教育，开展了一次“迈入青春门，走好人生路”的主题教育活动。假如你是该班的一名学生，请你积极参与以下活动。
已知sinα=13+cosα，且α∈（0，π2），则cos2αsinα+π4的值为____
根据表格内容，从题中所给的A、B、C、D四个选项中选出最佳答案。
Enjoy Harvesting
Want to relax yourself?
Want to experience country life?
Come and pick litchi!
Free for a taste.
Price:￥20 per kilo Dates: July 20th-July 28th
Add: Changlin village Tel:277-8688
Fitness Band on sale
Smartwatches without the watch
Monitor speed, time, distance, caloties burned, etc.
Long battery（电池）life (5 days)
￥800 （20% off for students)
Tel:289-6799
Visit Sam Mall for more information.
Ice and Snow Festival
Charming Ice Carving
Amazing World of Ice and Snow
Welcome to Fenghuang Park!
Dates: July 1st -July 25th
￥20 for each adult (half for each student)
Tel:288-6299
Super Pillow（枕头）Fight Party
Pillow Fight, a popular activity among young foreigners, has now come to Putian. It's a creative way to release(释放) pressure and stress.
Place:Putian Stadium
Time:2:30-5:00pm, June 28th
Fee:￥50 (pillow included)
Tel:275-6588
每年12月1日是“国际艾滋病预防日”，其主题是“全民动员，遏制艾滋，履行承诺”．下列关于病毒的叙述中，不正确的是（ ）
二次函数y=ax2+bx+c（a≠0）的图象如图所示，下列结论：①b＜0；②c＞0；③a+c＜b；④b2﹣4ac＞0，其中正确的个数是（ ）
的值为（ ）.（结果保留三个有效数字）
