Because ABCDEF is a regular hexagon, so angles abc bcd cde def efa fab are 120 degrees. Angles gaf lfe ked jdc icb hba are 90 degrees, that means angles gab hbc icd jde kef lfa are 30 degrees. Let gf=1, x=cos 30 degrees x 1 = sqrt(3)/2; ag=sin 30 degrees x 1 = 0.5. Because triangles agf and bha are congurent, that means ah=1, y=ah-ag=1-0.5=0.5.