The length of the hypotenuse, line segment gh, in triangle gjh measures 6 cm. line segment jh measures 2 cm.

Then you can calculate the length of the other segment, gj, using Pytagora's theorem, because when you are talking about hypotenuese you know that it is a right triangle.

hypotenuse^.2 = leg1^2 + leg2^2

(6 cm) ^2 = (2 cm) ^2 + (segment gj) ^2

segment gj^2 = 36 cm^2 - 4cm^2 = 32 cm^2

segment gj = √ (32 cm^2) = 5.66 cm