Given: In right ∆ABC, base BC = 12 cm, ∠B = 90° and AB + AC = 18 cm.
Required: To construct the right triangle ABC.
Steps of Construction:
1. Draw the base BC = 12 cm.
2. At the point B, make an ∠XBC = 90°.
3. Cut a line segment BD = AB + AC (= 18 cm) from the ray BX.
4. Join DC.
5. Draw the perpendicular bisector PQ of CD to intersect BD at a point A.
6. Join AC.
Then, ABC is the required right triangle.