If the radius of a circle is reduced by $40 \%$,then its circumference is reduced by (in $\%$).

If the area of a square increases by $69 \%$,then the side of the square increases by (in $\%$)

If the measures of a diagonal and the area of a rectangle are $25\, cm$ and $168\, cm^2$ respectively,what is the length of the rectangle? (in $cm$)

The perimeters of a circle,a square,and an equilateral triangle are the same,and their areas are $C$,$S$,and $T$ respectively. Which of the following statements is true?

The diameter of a circle is $105 \, cm$ less than its circumference. What is the diameter of the circle? (in $cm$)

$A$ playground has the shape of a rectangle with two semi-circles on its smaller sides as diameters,added outside. If the sides of the rectangle are $36 \, m$ and $24.5 \, m$,then the area of the playground is ......... $m^2$ (use $\pi = \frac{22}{7}$).