A tree makes a shadow on 2 meters. At the end of the tree there is a sighting line of 46 degrees. How tall is the tree?

The tree makes a right triangle.

From the corner angle of 46°, the line to the tree is the adjacent side (2 m), and the tree is the opposite side (x).

Using tangent:  tan(46°)  =  x / 2   --->   x  =  2 · tan(46°)   --->   x  =  2.1 meters

I'm assuming that you mean the line of sight from the tip of the shadow to the top of the tree is 46 degrees..if so, we can use the tangent function to solve this....the height of the tree is given by

Height = 2 * tan (46)