The circular measure of an angle of an isosceles triangle

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The circular measure of an angle of an isosceles triangle is (5π / 9) . Circular measure of one of the other angles must be

1. 5π
  18
2. 5π
  9
3. 2π
  9
4. 4π
  9

Correct Option: C

Using Rule 1,
Sum of remaining two angles

= π -		5π	=	4 π
		9		9

∴ Each angle =		1	×	4π	=	2π
		2		9		9

[∵ ∆ is isosceles]