Find the roots of the equations:
1. $\displaystyle sin(x)=x$
2. $\displaystyle cos(x)=x$
3. $\displaystyle tan(x)=x$
These are transcendental equations - which means that exact solutions cannot be found except for special cases eg. For 1. and 3. x = 0 is one of the solutions. To get the other solutions you will need to use technology to get decimal approximations of them.
This is only good if either:
1. You don't want very good accuracy in your solutions, or
2. You use technology to draw them and then get that same technology to find the x-coordinates of the intersection points.
You could also leave them in terms of $\displaystyle \pi$ though?
For example $\displaystyle \sin{x} = 0$ would have solutions of $\displaystyle 0 + {k}\pi $ where k is an integer
Note this only words if x is in radians, the small angle approximation (what sbcd90 describes) is a truncation of the Taylor series for sin, cos and tan respectively. It works because as x is much less than one it's powers will decrease rapidly.
$\displaystyle \sin{x} = x$
$\displaystyle \cos{x} = 1-\frac{x^2}{2}$
$\displaystyle \tan{x} = x$