A right triangle when one side is 3.5 cm and sum of other sides and the hypotenuse is 5.5 cm.

Step 1:
Draw ∠YBX = 90°.

Step 2:

With B as center and radius 3.5cm and 5.5cm respectively cut arcs intersecting BX at C and BY at Z.

Step 3:

Join ZC and construct its perpendicular bisector intersecting BY at A.

Step 4:
Join AC.

ABC is the required triangle.

Justification

Here ∠ABC=90° , BC=3.5cm by construction.

As A is the point of intersection of the perpendicular bisector and CZ,

So, AZ=AC which means AB+AZ=5.5cm

And at the same time AB+AC=5.5cm

Hence the triangle Construction is justified.