Question

Constuct triangle XYZ such that |XY|=8cm, angle YXZ =105° and angle XZY =45°

Answer 1

The classical definition of "construct" in geometry restricts your tool to
only a straightedge and a compass.
Since your are required to measure XY to be 8 cm, we are simply going
to draw it.
Start with a base of XY and measure it off at 8 cm/
Using a protractor, at X, measure an angle of 105°and draw a ray from X
at Y measure an angle of 30° and draw a ray from Y,
(you know 2 of the angles, so the missing angle = 180-105-45 = 30 )

Mark Z, the intersection of the rays.

That's it, your are done

Answer 2

If you don't have a protractor, it is easy to construct the 105° angle, since 105=90+15
So just make a 90° angle
make a 60° angle and bisect it twice to get the 15° angle
Then add them together.