Question

正弦定理：已知△ABC中，∠A=60°，a=根号3，求(a+b+c)/(sinA+sinB+sinC)的值

Answer 1

a/sinA=√3/(√3/2)=2
因为a/sinA=b/sinB=c/sinC
所以由合比定理
(a+b+c)/(sinA+sinB+sinC)=a/sinA=2

Answer 2

d
|x|<=2,|y|<=2
-2<=x<=2,
-2<=y<=2
所以就是乙x=2,x=-2,y=2,y=-2围城的正方形
面积是16

e
则是单位圆
所以面积是π

所以概率=π/16