What is the area of a triangle whose sides are $9\, cm$,$12\, cm$,and $15\, cm$? (in $cm^2$)

$A$ wire when bent in the form of a circle encloses an area of $1386 \, cm^2$. What will be the enclosed area when the same wire is bent into the form of an equilateral triangle?

$A$ wire is in the form of a circle of radius $42 \ cm$. It is bent into a square. The side of the square is? (in $cm$)

If the perimeter of a rectangular field is $200\, m$ and its breadth is $40\, m$,then its area is (in $m^2$):

In $\Delta ABC$,$AD$ and $AE$ are bisectors of $\angle BAC$ and $\angle BAD$ respectively. If $\angle BAE = 30^{\circ}$,$AE = 9 \text{ cm}$,and $EC = 15 \text{ cm}$,what is the area (in $\text{cm}^2$) of $\Delta AEC$?

The area of a circle is $154 \, cm^{2}$. The length of an arc of the circle which subtends an angle of $45^{\circ}$ at the centre is......$cm$.