You can only achieve success __________ hard work.
You can only achieve success __________ hard work.
During the Tang dynasty(唐朝), nearly everything produced in the world __________ on the streets of Chang’an.
—I don’t think sixteen-year-olds should be allowed to drive.
—I __________. It’s not safe.
—Congratulations! You __________ big progress in the last three years.
—Thank you, Mr. Li. I’ll never forget the good times in Junior High.
—Please show me your health code(6码), either on Wechat or Alipay.
—__________. Here it is
—Would you like to visit the National Science Museum with me tomorrow, Amy?
— __________.
—Can I have two tickets for the Chinese Poetic Dance?
— __________. All the tickets have been sold out.
[问题情境]
在一次数学兴趣小组活动中,小昕同学将一大一小两个三角 板按照如图1所示的方式摆放.其中∠ACB=∠DEB=90°,∠B=30°,BE=AC=3.
[问题探究]
小昕同学将三角板DEB绕点B按顺时针方向旋转.
(1)如图2,当点E落在边AB.上时,延长DE交BC于点F,求BF的长.
(2)若点C、E、D在同- -条直线上,求点D到直线BC的距离.
如图，四边形ABCD为平行四边形,延长AD到点E,使DE =AD,且BE⊥DC.
