It is given that the triangle is isosceles and the sides are 3 and 6.
Since the triangle is isosceles so third side will be either 3 or 6 .
If third side is 3 then we have
![3+3=6](https://img.qammunity.org/2023/formulas/mathematics/college/vie8jhulwp30chxi193zpfccg29suprp3y.png)
which is a contradiction to the fact that sum of two sides of a triangle is greater than the third side.
So the third side will be 6.
Hence the correct option is (A).