# Integral

#### Leiloio

##### New member
I was doing an probability problem and i have to do

thanks

#### Jomo

##### Elite Member
I would always start off an integral that has a trig function with letting the angle be u (unless the angle started off as x or u or v...)

Are you asking that someone here solves this for you? On this forum we prefer that the student solves their own problem with help from forum helpers. So please post back.

#### Leiloio

##### New member
Its a problem about probability, I have the solution ussing other ways, but i want to check if i´m doing well.There is not a student problem, its a problem from 2019 in Spain to select staff in order to teach maths in high school.
We have a isosceles triangle l, an angle is a random variable X between 0 and pi/2 X=kx(pi-x)
I have to calculate the expected value, and i try to do the integral... other people calculate the density function and made the integral, i thought i can do directly the integral from 0 to pi/2 x A(x)

#### MarkFL

##### Super Moderator
Staff member
According to W|A, that definete integral may be approximated by:

$$\displaystyle -0.210834676740899235446490727729394381940321035952272512618100274156737871242552076157591563972493302$$

The exact answer is given in terms of the Fresnel S and C integrals.