Method to calculate the circle area: 1. Create an input tag and receive the radius value; 2. Use "document.getElementById('id').value" to get the radius value in the input input box; 3. , use the area formula "area=3.14*(radius*radius)" to find the area of the circle.
The operating environment of this tutorial: Windows 7 system, JavaScript version 1.8.5, Dell G3 computer.
The specific condition is to enter a radius, then find the area, round to 2 decimal places,
Document 输入圆的半径:
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