# 9th grade (14y) + expression of a variable from formula - examples - page 3

- Triangular pyramid

It is given perpendicular regular triangular pyramid: base side a = 5 cm, height v = 8 cm, volume V = 28.8 cm^{3}. What is it content (surface area)? - Prism - box

The base of prism is a rectangle with a side of 7.5 cm and 12.5 cm diagonal. The volume of the prism is V = 0.9 dm^{3}. Calculate the surface of the prism. - Above Earth

To what height must a boy be raised above the earth in order to see one-fifth of its surface. - Rhombus diagonal

Area of rhombus is 224. One diagonal measures 33, find length of other diagonal. - Fire tank

Whole fire tank was discharged once in 5 days by first out by second in $n days. Once firefighters pumped out 6/13 of water out from the tank and then let the water flow out both drain. How long take empty the tank? - Trapezoid ABCD v2

Trapezoid ABCD has length of bases in ratio 3:10. The area of riangle ACD is 825 dm^{2}. What is the area of trapezoid ABCD? - Rectangular trapezoid

The rectangular trapezoid ABCD is: /AB/ = /BC/ = /AC/. The length of the median is 6 cm. Calculate the circumference and area of a trapezoid. - RT 11

Calculate the area of right tirangle if its perimeter is p = 45 m and one cathethus is 20 m long. - Volume and surface

Calculate the volume and surface area of the cylinder when the cylinder height and base diameter is in a ratio of 3:4 and the area of the cylinder jacket is 24 dm^{2}. - Moon

We see Moon in the perspective angle 28'. Moon's radius is 1740 km at the time of the full moon. Calculate the mean distance of the Moon from the Earth. - Quadrangular prism

The quadrangular prism has a volume 648 cm^{3}. Trapezoid which is its base has the dimensions bases: a = 10 cm, c = 5 and height v = 6 cm. What is the height of the prism? - Square pyramid

Calculate the volume of the pyramid with the side 5cm long and with a square base, side-base has angle of 60 degrees. - Trapezoid

Area of trapezoid is 135 cm^{2}. Sides a, c and height h are in a ratio 6:4:3. How long are a,c and h? Make calculation... - Euclid theorems

Calculate the sides of a right triangle if leg a = 6 cm and a section of the hypotenuse, which is located adjacent the second leg b is 5cm. - Square

If the length of the sides of the square we decrease by 25% decrease the content area of 28 cm^{2}. Determine the side length of the original square. - Flowerbed 2

Around the square flower bed in a park is sidewalk 2 m wide. The area of this sidewalk is 243 m^{2}. What is the area of the flowerbed? - Circle sector

Circular sector with a central angle 80 ° has area 1257 cm^{2}. Calculate its radius r. - RT and ratio

Right triangle whose cathetus are in a ratio 7:14 has hypotenuse 78 m long. How long are cathetus? - Swing

A child weighing 12 kg is sitting on a swing at a distance of 130 cm from the axis of rotation. How far away from the axis of rotation (center) must sit down his mother weighs 57 kg if she wants to be swing in balance? - Cone container

Rotary cone-shaped container has a volume 1000 cubic cm and a height 12 cm. Calculate how much metal we need for making this package.

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