Hi,
Please check Ex 12.2, 10 here http://teachoo.com/1859/547/Ex-12.2--10---An-umbrella-has-8-ribs-which-are-equally-spaced/category/Ex-12.2/
To learn Chapter 12 Areas of Circles NCERT, visit http://teachoo.com/subjects/cbse-maths/class-10th/ch12-10th-areas-related-to-circles/
Written on Feb. 28, 2017, 11:40 a.m.