Area of an equilateral triangle = half *half* \sqrt{3} = 4 root 3, if we have to double the size then multiply by 2, isn’t that right?
Area of Equilateral Triangle = (√3 / 4) × a²
Where a is the side length.
Here in this question,
a = 4
So initially, the area would be
A = (√3 / 4) × 4²
A = (√3 / 4) × 16
A = √3 × 4
We are looking to double the size (area), the new Area would be
A = 2 × (√3 × 4)
A = √3 × 8
The new side length s will be
(√3 / 4) × s² = √3 × 8
s² = 32
s = √32
s = 4√2
The side length increased from 4 to 4√2. That is a 40% increase in side length of the triangle