Steps of construction
Step I Firstly, we draw a rough sketch of triangle with given measures marked on it.
Step II Draw a line segment AB of length 3 cm.
Step III Draw an angle of 45° on point B and produce it to ray Y.
Step IV With B as centre, draw an arc of 3 cm which intersects ray BY at C.
Step V Join AC.
Thus, ΔABC is the required isosceles triangle.