The perimeter P of a triangle is given by the formula,

P = a+b+c

P= a+2b                                  (Given triangle is isosceles triangle (b=c))

P =14+2(9)                             (Substitute a = 14 cm and b = 9 cm)

P =14+18                                (Multiply: 2(9) =18)

  = 32 cm                                (Add : 14 + 18 = 32) 

Perimeter of a triangle is 32 cm