My answer is (2)
Total perimeter of circle=4P├н since we have 3/4 of it the perimeter of that part is 3P├н
Let us call A and B the intersection points between the circumference and the cord (base of the isosceles triangle), and O the center of the circumference.
AOB is a rectangle triangle because 1/4 of 360 is 90 degrees.
Since AO=BO it is also isosceles, so AB=2*sqrt(2)
With that and the height of the cone you can get both sides. Each side is =sqrt(2+25)=3*sqrt(3)
Total perimeter=3P├н + 3*sqrt(3) + 3*sqrt(3)=3P├н + 6*sqrt(3)