The area of an equilateral triangle is equal to ............

In a right-angled triangle,the length of the hypotenuse is $29\,cm$ and one of the sides forming the right angle is $21\,cm$. Then,the semi-perimeter of the triangle is ............ $cm$.

$A$ rhombus shaped field has green grass for $18$ cows to graze. If each side of the rhombus is $30\, m$ and its longer diagonal is $48\, m$,how much area of grass field will each cow be getting (in $, m^{2}$)?

$(1)$ Area of a rhombus $= \frac{1}{2} \times \ldots \ldots \ldots$
$(2)$ Area of a triangle $= \ldots \ldots \ldots$

The sides of a triangle measure $12 \ cm$,$35 \ cm$,and $37 \ cm$. Find the area of the triangle. (in $cm^2$)

$A$ triangle and a parallelogram have the same area. If the sides of the triangle are $10 \, cm$,$17 \, cm$,and $21 \, cm$,and the parallelogram stands on the base $12 \, cm$,find the height of the parallelogram. (in $, cm$)