Examples for 8th grade - page 16

  1. Square grid
    sit Square grid consists of a square with sides of length 1 cm. Draw in it at least three different patterns such that each had a content of 6 cm2 and circumference 12 cm and that their sides is in square grid.
  2. n-gon
    x-gon What is the side length of the regular 5-gon inscribed in a circle of radius 12 cm?
  3. Wood in the forest
    drevo The amount of wood in the forest was estimated at 7000 m3. How much wood will be in forest after 2 years if the annual growth of wood is 2.2% each year and logging 70 m3 each year?
  4. KLMN
    trapezium In the trapezoid KLMN is given this informations: 1. segments KL and MN are parallel 2. segments KL and KM has same length 3. segments KN, NM and ML has same length. Determine the size of the angle KMN.
  5. Reservoir + water
    cuboid_water Reservoir completely filled with water weighs 12 kg. After pouring off three quarters of the amount of water weights 3 kg. Calculate the weight and volume of the reservoir.
  6. Triangular pyramid
    tetrahedron1 Calculate the volume and surface area of a regular triangular pyramid whose height is equal to the length of the base edges 10 cm.
  7. Barrel 3
    sud-s-vodou Barrel with water has a weight 118 kg. When we get off 75% of water it has a weight 35 kg. How many kg has empty barrel?
  8. Free fall
    volny_pad Lloyd fall from height 7 m. Calculate the speed he hit the ground when falling with acceleration g = 9.81 m/s2
  9. Cylinder - h
    cylinder_2 Cylinder volume is 163 cm3. Base radius is 10 cm. Calculate the height of the cylinder.
  10. Height
    thales_law Is right that in any right triangle height is less or equal half of the hypotenuse?
  11. Moving
    movie Vojta left the house at three o'clockat 4 km/h. After half hour later went from the same place Filip by bicycle at speed 18 km/h. How long take Tilip to catch up Vojta and how far from the house?
  12. Rhombus
    rhombus2 Internal angles of rhombus is in ratio 2:3. How many times is the shorter diagonal longer than side of rhombus?
  13. Playing cards
    playing_cards How many possible ways are to shuffle 6 playing cards?
  14. Lead cube
    pb_cube Calculate the edge of the cube made ​​from lead, which weighs 19 kg. The density of lead is 11341 kg/m3.
  15. Train
    High-Speed-Train A passenger train traveled for 2 hours 74 km. 3.1 hours after its departure started fast train and caught it on 186 km. How many km/h is different its average speeds?
  16. Division
    bonbons Three siblings Helena, Oliver and George split the bag with candies on merit in the ratio 6:1:4. How many candies should each get if in bag were 88?
  17. Wire D
    semicircle_1 Wire length 1 m is bent so that it forms a semicircle circuit (including the diameter). Determine the radius of the semicircle.
  18. Right triangle
    right_triangles Calculate the missing side b and interior angles, perimeter and area of ​​a right triangle if a=10 cm and hypotenuse c = 16 cm.
  19. Rotating cone II
    cone Calculate area of surface of rotating cone with base radius r=19 cm and height h=9 cm.
  20. Triangle in circle
    triangle_in_circle Vertices of the triangle ABC lies on a circle with radius 3 so that it is divided into three parts in the ratio 4:4:4. Calculate the circumference of the triangle ABC.

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