XYZ is an issoceless triangle .Angle XY = Angle. XZ = 6cm and YXZ= 100° calculate angle YZ correct to 2 s.f.
The only information I can use is this:
XYZ is an isosceles triangle,
XZ = 6cm and angle YXZ= 100°
Your statement, "Angle XY = Angle" does not follow standard notation.
you did it correctly in angle YXZ= 100°, using 3 letters the middle letter representing the vertex of the angle.
So I will assume that each of the equal sides is 6 cm
so each of the base angles is (180-100)/2° or 40°
Let the base be 2x, then by dropping a perpendicular,
cos 40° = x/6
x = 6cos 40° = .... you push the buttons