What can be used to measure the length curvedline show below

One method to measure the length of a CURVED line.Step 1Take a long thin thread.Step 2Take an ink PEN and put some ink mark or any mark near one end of the thread.Step 3PLACE that MARKINGS at the starting of curved lineStep 4Place the thread along the curved line TILL the end of curved lineStep 5Again take the ink pen and mark the end of the curved line on the thread.Step 6Measure the distance between the two makings in the thread. It is equal to the length of the curved line.Second MethodIf thread is not available ,take a divider from your geometry box. Measure one centimetre or any suitable length with divider legs. Place over the curved line and measure the length of the line by turning divider legs no of times over the curved line. Multiply the number of turns with length between the divider legs. This is equal to the length of the curved line.