Question

Explain two methods those you can use to measure the length of a curved line.

Answer 1

Determine Diameter of Circle
Determine diameter of the larger circle containing the arc. If you have the radius as a given, multiply that number by 2. For example, a radius of 5 inches equals a diameter of 10 inches

Position Protractor to Measure Arc Angle
Determine the angle of the arc by centering the protractor on the center point of the circle. The flat line at the bottom of the protractor called the "zero edge" must overlay the radius line and the zero degree mark on the protractor must overlay the bottom point of the arc.

Determine Angle Degrees
Note where the top point of the arc meets the protractor's degree scale. Wherever the arc ends defines the angle. For example, if the top point of the arc matches up to the 40 degree mark, your angle equals 40 degrees.

Multiply Diameter by Pi and Arc Angle
Multiply the diameter by 3.14 and then by the angle. In the examples used above with a diameter of 10 inches. and an angle of 40 degrees, you would use the following equation: 10 x 3.14 x 40, which equals 1256.

Divide by Total Degrees
Divide this product by 360 since there are 360 total degrees in a circle. In our example, this would be 1256 divided by 360 which equals 3.488.

Round Decimal Result
Round up the decimal if necessary to define the length of the arc. In our example, you could call the arc 3.49 inches if you round to hundredths or 3.5 inches if you round to tenths.