(c) 300%.Let a, b, c be the sides of the original triangle and s be its semi-perimeter.Then, s = \(rac{1}{2}\)(a+b+c)Let s1 be the semi-perimeter of the new triangle. Then,s1 = \(rac{1}{2}\) (2a + 2b + 2c) = (a + b + c) = 2s∴ Area A of original Δ = \(\sqrt{s(s-a)(s-b)(s-c)}\) and Area A1 of new Δ = \(\sqrt{s_1(s_1-2a)(s_1-2b)(s_1-2c)}\)= \(\sqrt{2s(2s-2a)(2s-2b)(2s-2c)}\)= 4\(\sqrt{s(s-a)(s-b)(s-c)}\) = 4A.∴ Percentage increase in area = \(\bigg(rac{A_1-A}{A} imes100\bigg)\)%= \(rac{(4A-A)}{A} imes100\)% = 300%.