Let the arc AC of a circle subtend a right angle at the centre O. If the point B on the arc AC, divides the arc AC such that length of arc ABlength of arc BC= 15, and OC= OA+ OB, then + 2( 3-1) is equal to
- 2 3
- 5 3
- 2+ 3
- 2- 3
Answer
(4) 2- 3
Solution
Arcs are in the ratio of the angles at the centre (1 : 5): AOB=15 , BOC=75
[figure]
Unit circle: OA=(1,0), OB=( 15 , 15 ), OC=(0,1)
y: 1= 15 = 6+ 2; x: 0= + 15 =-(2+ 3)
2( 3-1) =( 3-1)(2 3+2)=4
+ 2( 3-1) =2- 3
Answer: (4)