Steps of Construction :
(1) Draw a line PQ = 6 cm.

(2) Using compass taking P as centre draw an angle ∠P = 60°.
(3) Using compass taking Q as a centre draw an angle ∠Q = 30°.
(4) PS and QT intersect each other R.
(5) ΔRPQ is the required triangle.
On measuring; ∠R = 90°, length of PR = 3 cm.