8º Ano - Quiz De MatemÁtica Da Profª Schayla S2

1. Qual é a área de um retângulo cuja base mede 10 cm e a altura mede a metade da medida da base?

10 cm²

30 cm²

50 cm²

100 cm²

The area of a rectangle is calculated by multiplying the length of the base by the height. In this case, the base measures 10 cm and the height is half the measure of the base. Therefore, the height is 10/2 = 5 cm. The area of the rectangle is then calculated as 10 cm * 5 cm = 50 cm².

Explanation

The area of a rectangle is calculated by multiplying the length of the base by the height. In this case, the base measures 10 cm and the height is half the measure of the base. Therefore, the height is 10/2 = 5 cm. The area of the rectangle is then calculated as 10 cm * 5 cm = 50 cm².

2. Todo diâmetro é uma corda e toda corda é um diâmetro.

Verdade

Falso

This statement is false. Not every diameter is a chord, and not every chord is a diameter. A diameter is a line segment that passes through the center of a circle and has both endpoints on the circle. On the other hand, a chord is a line segment that connects two points on the circumference of a circle. While every diameter is a chord because it connects two points on the circumference, not every chord is a diameter because it may not pass through the center of the circle.

Explanation

This statement is false. Not every diameter is a chord, and not every chord is a diameter. A diameter is a line segment that passes through the center of a circle and has both endpoints on the circle. On the other hand, a chord is a line segment that connects two points on the circumference of a circle. While every diameter is a chord because it connects two points on the circumference, not every chord is a diameter because it may not pass through the center of the circle.

3. O diâmetro é a maior corda de uma circunferência.

Verdade

Falso

The statement is true because the diameter is defined as the longest chord of a circle. A chord is a line segment that connects two points on the circumference of a circle, and the diameter is the chord that passes through the center of the circle. Therefore, the diameter is always longer than any other chord of the circle.

Explanation

The statement is true because the diameter is defined as the longest chord of a circle. A chord is a line segment that connects two points on the circumference of a circle, and the diameter is the chord that passes through the center of the circle. Therefore, the diameter is always longer than any other chord of the circle.

4. A = (D.d)/2 é a fórmula para calcular a área de que figura geométrica plana?

Losango

Trapézio

Paralelogramo

Triângulo

The formula A = (D.d)/2 is used to calculate the area of a Losango, which is a geometric figure with four equal sides that form two pairs of opposite angles that are equal.

Explanation

The formula A = (D.d)/2 is used to calculate the area of a Losango, which is a geometric figure with four equal sides that form two pairs of opposite angles that are equal.

5. Se uma circunferência tem 10 cm de diâmetro, então qual é o seu comprimento aproximado?

13,14 cm

21,9 cm

27,6 cm

31,4 cm

The circumference of a circle can be found by multiplying its diameter by π (pi). In this case, the diameter is given as 10 cm. So, the circumference can be calculated as 10 cm * π. Since the value of π is approximately 3.14, the approximate circumference is 10 cm * 3.14 = 31.4 cm.

Explanation

The circumference of a circle can be found by multiplying its diameter by π (pi). In this case, the diameter is given as 10 cm. So, the circumference can be calculated as 10 cm * π. Since the value of π is approximately 3.14, the approximate circumference is 10 cm * 3.14 = 31.4 cm.

6. Podemos utilizar o teorema de Pick para calcular a área de qualquer polígono sobre uma malha quadriculada. Qual a área do triângulo abaixo?

7 unidades de área

8 unidades de área

9 unidades de área

16 unidades de área

The area of a triangle can be calculated using the formula A = (b * h) / 2, where b is the base of the triangle and h is the height. In this case, the base of the triangle is 4 units and the height is 4 units. Plugging these values into the formula, we get A = (4 * 4) / 2 = 8 units of area. Therefore, the correct answer is 8 units of area.

Explanation

The area of a triangle can be calculated using the formula A = (b * h) / 2, where b is the base of the triangle and h is the height. In this case, the base of the triangle is 4 units and the height is 4 units. Plugging these values into the formula, we get A = (4 * 4) / 2 = 8 units of area. Therefore, the correct answer is 8 units of area.

7. O que é o número PI?

A razão entre o comprimento de uma circunferência e o seu diâmetro.

A razão entre o comprimento de uma circunferência e o seu raio.

A razão entre o diâmetro e o raio de uma circunferência.

A razão entre o diâmetro e uma corda qualquer da circunferência.

The correct answer is "The ratio between the circumference of a circle and its diameter." This answer accurately describes what the number PI represents, which is the constant ratio between the distance around a circle and its diameter.

Explanation

The correct answer is "The ratio between the circumference of a circle and its diameter." This answer accurately describes what the number PI represents, which is the constant ratio between the distance around a circle and its diameter.

8. Minha horta circular tem 5 m de raio. Pretendo colocar 2 voltas de arame farpado ao seu redor. Quantos metros de arame farpado devo comprar?

31,4 m

62,8 m

15,7 m

49,5 m

To calculate the length of the wire needed, we need to find the circumference of the circular garden. The formula for the circumference of a circle is C = 2πr, where r is the radius of the circle. In this case, the radius is given as 5 m. Plugging this value into the formula, we get C = 2 * 3.14 * 5 = 31.4 m. However, since we want to put two layers of barbed wire, we need to double this length, giving us a total of 62.8 m of barbed wire needed.

Explanation

To calculate the length of the wire needed, we need to find the circumference of the circular garden. The formula for the circumference of a circle is C = 2πr, where r is the radius of the circle. In this case, the radius is given as 5 m. Plugging this value into the formula, we get C = 2 * 3.14 * 5 = 31.4 m. However, since we want to put two layers of barbed wire, we need to double this length, giving us a total of 62.8 m of barbed wire needed.

9. Qual é a medida aproximada do diâmetro de uma praça circular, cujo comprimento da sua circunferência é de 69 m?

6 m

15 m

22 m

31 m

A circunferência de uma praça circular é encontrada utilizando a fórmula C = πd, onde C é o comprimento da circunferência e d é o diâmetro. Dado que o comprimento da circunferência é de 69 m, podemos substituir na fórmula e encontrar o valor de d. Portanto, 69 = πd. Dividindo ambos os lados por π, encontramos que d ≈ 22 m. Portanto, a medida aproximada do diâmetro da praça é de 22 m.

Explanation

A circunferência de uma praça circular é encontrada utilizando a fórmula C = πd, onde C é o comprimento da circunferência e d é o diâmetro. Dado que o comprimento da circunferência é de 69 m, podemos substituir na fórmula e encontrar o valor de d. Portanto, 69 = πd. Dividindo ambos os lados por π, encontramos que d ≈ 22 m. Portanto, a medida aproximada do diâmetro da praça é de 22 m.

10. Resolvi bancar o atleta e correr em uma pista de corrida circular. Quero correr pelo menos 5 km. Sabendo que essa pista tem 25 m de raio, qual é o mínimo de voltas que preciso dar para chegar aos 5 km?

38 voltas

32 voltas

26 voltas

14 voltas

To find the minimum number of laps needed to run 5 km on a circular track with a radius of 25 m, we need to calculate the total distance covered in one lap and then divide 5 km by that distance. The distance covered in one lap can be calculated using the formula for the circumference of a circle, which is 2πr. Plugging in the radius of 25 m, we get a lap distance of 2π(25) = 50π m. To convert this to km, we divide by 1000, giving us 50π/1000 = 0.1571 km per lap. Dividing 5 km by 0.1571 km per lap, we get approximately 31.83 laps. Since we can't run a fraction of a lap, we round up to the nearest whole number, which is 32 laps. Therefore, the correct answer is 32 laps.

Explanation

To find the minimum number of laps needed to run 5 km on a circular track with a radius of 25 m, we need to calculate the total distance covered in one lap and then divide 5 km by that distance. The distance covered in one lap can be calculated using the formula for the circumference of a circle, which is 2πr. Plugging in the radius of 25 m, we get a lap distance of 2π(25) = 50π m. To convert this to km, we divide by 1000, giving us 50π/1000 = 0.1571 km per lap. Dividing 5 km by 0.1571 km per lap, we get approximately 31.83 laps. Since we can't run a fraction of a lap, we round up to the nearest whole number, which is 32 laps. Therefore, the correct answer is 32 laps.