1 1. "Circumcision" founded by Liu Hui, an ancient mathematician in China, can estimate pi, which can be calculated to any accuracy in theory. Zu Chongzhi inherited and developed "Pi", which made the value of π accurate to seven decimal places, leading the world for more than 1000 years. The first step of "secant" is to calculate the area s of the unit circle inscribed with a regular hexagon, where =.
The answer to this question is three times that of the root number three.
12. known ab∈R, (a+bi)? =3+4i(i is an imaginary unit), so a? +b？ =，ab= .
The answer to this question is 5 2.
14. Known △ABC, AB=AC=4, BC=2. Point D is a point on the extension line of AB, BD=2, and CD is connected, so the area of △BDC is _ _ _ _ _ _ _ _ _, and COS ∠ BDC is _ _ _ _ _ _.
The answer to this question is the root number fifteen.
15. Assuming that vectors A and B satisfy è a 乸 = 1 and 乸 b 乸 =2, the minimum value of 乸 a+b 乸 a-b 乸 is _ _ _
The answer to this question is 4, twice as much as the root number 5.
16. From 8 students (6 men and 2 women * * *), the team leader 1, vice captain 1 and ordinary players are selected to form a 4-person service team. The service team is required to have at least 1 female, and * * * has different selection methods in _ _ _ _ _ _. (Answer with numbers)
The answer to this question is 660.
17. Given α∈R, the maximum value of the function f(x) is 丨 x+4/丨 α+α is 5, so the value range of α is _ _ _ _ _ _ _.
The answer to this question is (negative infinity, 9/2)
The above are some questions and answers in the liberal arts mathematics test paper of Zhejiang college entrance examination for reference only.