$A$ piece of wire $132 \, cm$ long is bent successively in the shapes of an equilateral triangle,a square,a regular hexagon,and a circle. Then,which has the largest surface area?

If the height of an equilateral triangle is $2 \sqrt{3} \text{ cm}$,then the length of its side is ...... $\text{cm}$.

If the area of a square is equal to the area of a rectangle $6.4 \, m$ long and $2.5 \, m$ wide,then each side of the square measures (in $m$)

In measuring the sides of a rectangle,one side is taken $5 \%$ in excess,and the other $4 \%$ in deficit. Find the error percent in the area calculated from these measurements. (in $\%$)

If the length and breadth of a rectangular room are each increased by $1\, m$,then the area of the floor is increased by $21\, m^2$. If the length is increased by $1\, m$ and the breadth is decreased by $1\, m$,then the area is decreased by $5\, m^2$. The perimeter of the floor is.......$m$.

$A$ drawing room is $7.5 \text{ m}$ long,$6.5 \text{ m}$ broad,and $6 \text{ m}$ high. Find the length of paper $2.5 \text{ dm}$ wide required to cover its walls,allowing $8 \text{ m}^2$ for doors.