# Examples for 8th grade - page 44

- Semicircle

To a semicircle with diameter 10 cm inscribe square. What is the length of square sides? - Rectangle

The rectangle is 18 cm long and 10 cm wide. Determine the diameter of the circle circumscribed to rectangle. - Dig water well

Mr. Zeman digging a well. Its diameter is 120 cm, and plans to 3.5 meters deep. How long (at least) must be a ladder, after which Mr. Zeman would have eventually come out? - Rectangular trapezoid

Calculate the content of a rectangular trapezoid with a right angle at the point A and if |AC| = 4 cm, |BC| = 3 cm and the diagonal AC is perpendicular to the side BC. - Wheel

How many times turns the wheel of a passenger car in one second if car run at speed 89 km/h. Wheel diameter is d = 62 cm. - The carpet

How many meters of carpet 90 cm wide need to cover floor room which has a rectangular shape with a lengths 4.8 m and 2.4 m if the number of pieces on the carpet is needed to be lowest? - Round table tablecloth

Round table has area 50.24 dm^{2.}Calculate the diameter of the circular tablecloth, if it is extend beyond the edge of the table by 30 cm. - Canister

Gasoline is stored in a cuboid canister having dimensions 44.5 cm, 30 cm, 16 cm. What is the total weight of a full canister when one cubic meter of gasoline weighs 710 kg and the weight of empty canister is 1.5 kg? - Parcel

Both dimensions of the rectangular parcel were increased by 40%. By how many % has increased its acreage? - Midpoint of segment

Point A has coordinates [15; 1] and the midpoint of the segment AB is the point [-20; 13]. What are the coordinates of point B? - Barrel 2

Empty barrel weighs 12 kg. When it filled with water up to 46% height, weighs 68 kg. How heavy is barrel full of water? - RT 10

Area of right triangle is 17 cm^{2}and one of its cathethus is a=8 cm. Calculate perimeter of the triangle ABC. - Olympics

In how many ways can be placed 6 athletes on the podium at the Olympics? Depend on the color of the metal. - Wheels

Small tractor wheel with a diameter of 60 cm must be rotated 8 times to overcome some pathway. How many times must turn the big tractor wheel with a radius 60 cm to overcome the same distance? - Bicycles

You're the owner of the transport 's learning playground. Buy bicycles of two colors but you've got to spend accurately 120000 Kč. Blue bike costs 3600Kč and red bicycle 3200Kč. - Oil tank and pipes

The underground oil tank can be filled by two oil pipelines. The first is filled in 72 hours and the second in 48 hours. How many hours from the moment when first pipeline began to fill the oil is it necessary to start filling it with the second to fill in - Total displacement

Calculate total displacement of the 12-cylinder engine with the diameter of the piston bore B = 6.8 cm and stroke S=2 cm of the piston. Help: the crankshaft makes one revolution while the piston moves from the top of the cylinder to the bottom and back t - Silo

Outer perimeter of silo is 24 m. Concrete wall is 18 cm thick. What is diameter and area of inside floor of silo? - Rhombus

ABCD is a rhombus, ABD is an equilateral triangle and AC is equal to 4. Find the area of the rhombus. - Miraculous tree

Miraculous tree grows so fast that the first day increases its height by half the total height of the second day by the third, the third day by a quarter, etc. How many times will increase its height after 8 days?

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