# Four circles

1) Calculate the circle radius if its area is 400 cm square
2) Calculate the radius of the circle whose circumference is 400 cm.
3) Calculate circle circumference if its area is 400 cm square
4) Calculate the circle's area if perimeter 400 cm.

Result

r1 =  11.284 cm
r2 =  63.662 cm
o1 =  70.899 cm
S2 =  12732.405 cm2

#### Solution:

Leave us a comment of example and its solution (i.e. if it is still somewhat unclear...):

Be the first to comment!

## Next similar examples:

1. Circle - easy 2
The circle has a radius 6 cm. Calculate:
2. Circle r,D
Calculate the diameter and radius of the circle if it has length 52.45 cm.
3. Cable
Cable consists of 8 strands, each strand consists of 12 wires with diameter d = 0.5 mm. Calculate the cross-section of the cable.
4. Circle - simple
Calculate the area of a circle in dm2, if its circumference is 31.4 cm.
5. Area to perimeter
Calculate circle circumference if its area is 254.34cm2
6. Perimeter to area
Calculate the area of a circle with the perimeter 15 meters.
Determine the radius of the circle, if its perimeter and area is the same number.
8. Right triangle ABC
Calculate the perimeter and area of a right triangle ABC, if you know the length of legs 4 cm 5.5 cm and 6.8 cm is hypotenuse.
9. Circle
What is the radius of the circle whose perimeter is 6 cm?
10. CD disc
A compact disc has a diameter of 11.8 cm. What is the surface area of the disc in square centimeters?
11. Diameter
What is the inside diameter of the cylinder container and if half a liter of water reaches a height 15 cm?
12. Sidewalk
The city park is a circular bed of flowers with a diameter of 8 meters, around it the whole length is 1 meter wide sidewalk . What is the sidewalk area?
13. Lawns
Before a sports hall are two equally large rectangular lawns, each measuring 40 m and 12 m. Maintenance of 10m² lawn cost 45 CZK yearly. On each lawn is circular flowerbed with a diameter 8 meters. How much money is needed each year to take on lawn care?.
14. Mine
Wheel in traction tower has a diameter 5 m. How many meters will perform an elevator cabin if wheel rotates in the same direction 49 times?
15. Flowerbed
In the park there is a large circular flowerbed with a diameter of 12 m. Jakub circulated him ten times and the smaller Vojtoseven times. How many meters each went by and how many meters did Jakub run more than Vojta?
16. Well
Rope with a bucket is fixed on the shaft with the wheel. The shaft has a diameter 50 cm. How many meters will drop bucket when the wheels turn 15 times?
17. Simplify 2
Simplify expression: 5ab-7+3ba-9