Let the wire is cut into 2 pieces of length y&20-y
Therefore side of square will be =4y and hexagon will be =620−y
Area of square=(4y)2
Area of hexagon=6×43(620−y)2
Total area=16y2+243(20−y)2
On differentiating,
A′(y)=162y+2423(20−y)(−1)
A′(y)=0aty=3+23403
Length of side of regular hexagon=61(20−y)=61(20−3+23403)=3+2310