In a quadrilateral, the length of the altitudes drawn onto a diagonal is $9 cm and 12 cm$. If its area is $420 c{m}^2$, then the length of the diagonal is .

  

The area of a circle of radius $7 cm$ is _____ $c{m}^2$

If the volume of a cube is $27 c{m}^3$, then the length of its edge is _____ $c{m}^3$

If the radius of a circle is $7 cm$, then the circumference of the circle is _____.

A cube of edge $9 cm$ is cut into $x$ cubes of each of edges $3 cm$. Then the value of $x$ is _____.

If the base of a triangle is $5 cm$ and its area is $20 c{m}^2$, then the height of the triangle is _____.

If the angle of a sector is $30°$ and the radius of the sector is $21 cm$, then the length of the arc of the sector is ____.

Find the perimeter of a square whole area is $225 m^2$.

The area of a parallelogram is $50 c{m}^2$. If the base is $10 cm$, then find its corresponding height.