Hello Basant
Circumference of 1st semicircle = π × 1/2 = π × 0.5
Circumference of 2nd semicircle = π × 2/2 = π × 1
Circumference of 3rd semicircle = π × 3/2 = π × 1.5
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Circumference of 13th semicircle = π × 13/2 = π × 6.5
Written on Sept. 3, 2017, 9:10 p.m.