Steps of Construction :
(i) Draw a triangle ABC with side BC = 7 cm, ∠B = 45°, ∠A = 105°.
(it) Draw any ray BX making an acute angle with BC on the side opposite to the vertex A.
(iii) Along BX, mark off 4 points B1, B2, B3 and B4 on BX such that BB1 = B1B2 = B2B3 = B3B4
(iv) Join B3 to C and draw a line through B4 parallel to B3C, intersecting the extended line segment BC at C’.
(v) Draw a line through C’ parallel to CA intersecting the extended line segment BA at A’.
Then A ‘BC’ is the required triangle. Justification :