1, calculated by radius (r): the formula of the area of a circle is A=πr? , where π is a number about 3. 14 159. You can substitute the given radius value into this formula and then calculate it. Calculated by the diameter (d): the diameter is the distance between two points passing through the center of the circle. The diameter of a circle is usually twice the radius. In this case, the formula of circular area is A=(π/4)d? .
2. Calculated by perimeter (c): perimeter is the length of the circular boundary. The formula of the circumference of a circle is c = 2π r. If the circumference is known instead of the radius or diameter, you can use this formula to calculate the area of the circle. First, the radius r is calculated by the perimeter formula. Then, substitute the radius value into the area formula A=πr? To calculate.
Correct steps to solve mathematical problems
1. Reading comprehension questions: Read the questions carefully to ensure that you understand the information, requirements and conditions given. Mark key information and relationships. Formulate solutions: according to the requirements and conditions of the problem, determine the appropriate mathematical concepts, formulas and methods.
2. Analyze the problem: analyze the structure and characteristics of the problem, and identify and apply appropriate mathematical principles and skills. Carry out calculation: carry out mathematical calculation and use correct formulas, mathematical rules and operators. Make sure that data and variables are substituted into the correct positions before calculation.
3. Check the answer: check the solution to ensure the accuracy of calculation and the consistency of logic. You can re-examine the question, make an estimate or verify the answer in other ways. Review and reflection: review the process of solving problems and evaluate the effectiveness and efficiency of solutions. Think about whether there are other methods or strategies to solve the problem better.
4. Present the solution: present the solution in a clear, organized and logical way, including calculation steps, intermediate results and final answers. Use appropriate mathematical symbols and marks to make the solution easy to understand and verify. Find the known and unknown: determine the given known information and the required unknown quantity in the problem. This helps to determine the mathematical formula and method to be used.