doing the Sin and Cos and Tan (and E^it ) work.

If you mean, where I actually work out the opposite length of a triangle from the angle by hand on a piece of paper... maybe once a year.

If you mean a higher level calculation that HAS sin and cos in it that tools like matlab or whatever are using sin and cos ... all the time ... probably at least once a week.

and if you mean (and I doubt this is what you are getting at) where something I use is using sin and cos or tan ... then literally every second all day long ... from frequency based communication protocols to speedometers to clocks and on and on ... that HAVE sin and cos in them and I KNOW that it is because sin and cos are built in.... but luckily for me, the computers are the ones actually working that out every second ....