Mathematics Grade 5 Exercise Book Page 100 Practice

Guidelines for solving Mathematics Grade 5 Exercise Book Page 100: Practice (including solution methods)

1. Solving Exercise 1 - Mathematics Grade 5 Exercise Book Page 100: Practice

Problem:
Calculate the area of a circle with radius r:
a) r = 6cm;                                                   b) r = 0.35dm.

Solution method:
- Apply the formula for calculating the area of a circle when given the radius (r): A = r x r x 3.14 (Value of pi = 3.14).
- Substitute the corresponding values into the formula, carefully calculate to find the most accurate result.

Answer:
a) The area of a circle with radius r = 6cm is 6 x 6 x 3.14 = 113.04 (cm²)
b) The area of a circle with radius r = 0.35dm is 0.35 x 0.35 x 3.14 = 0.38465 (dm²)
    Answer: a) 113.04 (cm²);
                 b) 0.38465 (dm²).

2. Guidelines for solving Exercise 2 - Solve Math 5 Practice Page 100

Problem:
Calculate the area of a circle knowing the circumference C = 6.28cm.

Solution method:
- Step 1: From the formula for calculating the circumference of a circle: C = d x 3.14, we can calculate the diameter of the circle: d = C : 3.14 (d is the diameter).
- Step 2: Knowing the diameter, we can deduce the length of the radius: r = d : 2.

Answer:
The diameter of the circle is:
6.28 : 3.14 = 2 (cm)
The radius of the circle is:
            2 : 2 = 1 (cm)
The area of the circle is:
           1 x 1 x 3.14 = 3.14 (cm²)
                             Answer: 3.14cm²

3. Guidelines for solving Exercise 3 - Mathematics

Solution:
- Step 1: Calculate the area of the well mouth using the formula for the area of a circle when the radius is given (r): A = r x r x 3.14 (The value of pi = 3.14).
- Step 2: Calculate the radius of the large circle by adding the radius of the well mouth to the radius of the well.
- Step 3: Apply the formula C = r x r x 3.14 to calculate the area of the large circle.
- Step 4: Calculate the area of the well wall by subtracting the area of the large circle (previously calculated) from the area of the well mouth (small circle).

Answer:
The area of the small circle (well mouth) is:
            0.7 x 0.7 x 3.14 = 1.5386 (cm²)
The radius of the large circle is:
            0.7 + 0.3 = 1 (m)
The area of the large circle is:
            1 x 1 x 3.14 = 3.14 (cm²)
The area of the well wall is:
            3.14 - 1.5386 = 1.6014 (m²)
 Answer: 1.6014 (m²).

Guidelines for solving Math Grade 5 Exercise Page 100, Practice (concise)

Exercise 1 Page 100 SGK Toán 5
Calculate the area of a circle with radius r:
a) r = 6cm; b) r = 0.35dm.
Answer: a) 113.04 (cm²); b) 0.38465 (dm²)

Exercise 2 - Solve Math 5 Practice Page 100
Calculate the area of a circle knowing the circumference C = 6.28cm.
According to the problem, we have: d x 3.14 = C
d x 3.14 = 6.28
d = 6.28 : 3.14
d = 2
So the diameter of the circle is 2cm
The radius of the circle is: 2 : 2 = 1(cm)
The area of the circle is: 1 x 1 x 3.14 = 3.14 (cm²)
Answer: 3.14 (cm²).

"""-- END """"

 Note:

Referring to and completing all Math problems about circles for Grade 5 with answers, basic and advanced, students can easily solve all advanced and basic problems related to circles.

In addition to the above content, students can explore the section Subtracting two decimal numbers to prepare for the content of this lesson in the Grade 5 Mathematics curriculum.

Here are some tips for Solving 5th Grade Math Problems on page 100, Practice in full detail. Prepare for the content of the Practice section on pages 100, 101 Math Textbook by going through the Solving 5th Grade Math Problems on pages 100, 101 section, focusing on exercises, and the Introduction to pie charts through the Solving 5th Grade Math Problems on page 102 section to improve your understanding of 5th-grade Math.