How to solve this Question

Dear student,
Given perimeter of equilateral triangle = 36 cm
Let the side of equilateral triangle be 'a' cm
Hence 3a = 36
Therefore, a = 12 cm
Area of equilateral triangle = (√3/4) x a² sq units
                                      = (√3/4) x 12²
                                      = (√3/4) x 144 = 36√3 sq cm
                                      = 62.3 sq cm
 Regards