题目内容：

设随机变量X的密度函数为f(x)=Acosx,-π/2

优质解答

F(x)=∫Acosxdx|[-π/2,π/2]=1
∫Acosxdx
=A∫cosxdx
=Asinx+C
F(x)=∫Acosxdx|[-π/2,π/2]
=sin(π/2)-sin(-π/2)
=A-(-A)
=2A=1
∴A=1/2
P(0