If the perimeter of an equilateral triangle is $12\, m$,then find its area.

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

The ratio of the area of the incircle and circumcircle of a square is?

$A$ wire bent in the form of a circle of radius $42 \, cm$ is bent in the form of a rectangle whose sides are in the ratio of $6:5$. The smaller side of the rectangle is (in $cm$)

Inside a square plot,a circular garden is developed which exactly fits in the square plot and the diameter of the garden is equal to the side of the square plot which is $28\, m$. What is the area of the space left out in the square plot after developing the garden? (in $m^2$)

The ratio between the areas of two circles is $4: 7.$ What will be the ratio of their radii?