Given that,

Two sides of triangle are 12 cm and 14 cm respectively

Also,

Perimeter of triangle = 36 cm

We know that,

Perimeter of triangle = Sum of all sides of a triangle

36 = 12 + 14 + Side

36 = 26 + Side

Side = 36 – 26

Side = 10 cm

Therefore, the third side of the triangle be 10 cm