Examples for 8th grade - page 29

  1. 30-60-90
    30-60-90 The longer leg of a 30°-60°-90° triangle measures 7. What is the length of the shorter leg?
  2. Field with vegetables
    irrigation Field planted with vegetables has shape of a rectangular isosceles triangle with leg length of 24 m. At the vertices of the triangle are positioned rotating sprinklers with a range of 12 m. How much of the field sprinkler doesn't irrigated?
  3. Chicken
    sliepka I threw three chicken for a handful of grains and I noticed that it eat in a ratio of 8:7:6 and two of them grabbed 156 grains. How many grains have fought that chicken?
  4. Flowerbed 2
    flowerbed Around the square flower bed in a park is sidewalk 1.4 m wide. The area of ​​this sidewalk is 125 m2. What is the area of the flowerbed?
  5. RT and ratio
    triangles Right triangle whose cathetus are in a ratio 6:17 has hypotenuse 47 m long. How long are cathetus?
  6. Diamond ABCD
    kosoctverec2 In the diamond ABCD is the diagonal e = 24 cm and size of angle SAB is 28 degrees, where S is the intersection of the diagonals. Calculate the circumference of the diamond.
  7. Children pool
    hexagon_prism2 The bottom of the children's pool is a regular hexagon with a = 60 cm side. The distance of opposing sides is 104 cm, the height of the pool is 45 cm. A) How many liters of water can fit into the pool? B) The pool is made of a double layer of plastic film.
  8. Cube - wall
    cubes_2 V kocke ABCDEFGH je ?. Aký je povrch kocky?
  9. Cuboid 5
    drevo_1 Calculate the weight of the cuboid with dimensions of 12 cm; 0.8 dm and 100 mm made from spruce wood (ς = 550 kg/m3).
  10. Number
    sqrt_2 Is number 4.764023 irrational?
  11. Base
    triangle_2 Compute base of an isosceles triangle, with the arm a=9 cm and a height above the base h=6 cm.
  12. Bath
    bathroom In the bath is 30 liters of hot water. Then added 38 liters of cold water at temperature of 17 °C decreased temperature of water to 48 °C. What was the initial temperature of the hot water?
  13. Father and son
    father_sin Father is three times older than his son. 12 years ago father was nine times older than the son. How old are father and son?
  14. Water
    storm_1 On the lawn which has area 243 m2 rained 5 mm of water. How many liters of water rained?
  15. Crown
    2_kcs Siblings collect a 2-crowns and 5-crowns. Together have 80 coins with a total of value 310 crowns. How many saved two-crowns and how many five-crowns?
  16. Sprayers
    postrekovac The vineyard can be sprayed first sprayer in 5 hours and with the second in 7 hours. How long would it take if we use sprayers both at once?
  17. Exam average
    vysvedcenie_2 Average of marks that have on the certificates students of 8.A class in mathematics is exactly 2.45. If we did not add 1 and 3 of sutdents Michael and Alena, who arrived a month ago, it would average exactly 2.5. Determine how many students have class 8.
  18. The body
    body_cubes The body on the figure consists of cubes with an edge length 10 cm. What surface has this body?
  19. Mother and daughter
    mom_daughter Three years ago mother was three times older than daughter. After nine years she will be only twice old. How old is mother (and daughter)?
  20. Diagonal
    rectangles2 Diagonal of the rectangle has length 14 cm. Angle between diagonal and londer sife of rectangle is 37°. Calculate area of the rectangle.

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