Question

If OB= 17 and AB = 30, then OR =

Answer 1

The correct answer is 8
Because
In triangle ORB
OR=(OB^2-RB^2)^1/2
OR=(17^2-15^2)^1/2
OR=(289-225)^1/2
OR=(64)^1/2
OR=8
RB=AB/2 so I kept its value 15 and ^1/2 refers to square root

Answer 2

Option A.

Explanation:

Given information: OB= 17 and AB = 30

If a line is perpendicular to a chord of a circle and passes through the centre of the circle, then it bisects that chord.

Using this definition we can say that point R is the midpoint of AB.

`RB=(AB)/(2)`

`RB=(30)/(2)`

`RB=15`

According to the Pythagoras theorem, in a right angle triangle

`hypotenuse^2=base^2+perpendicular^2`

Using Pythagoras theorem in triangle ORB,

`OB^2=RB^2+OR^2`

`(17)^2=(15)^2+OR^2`

`289=225+OR^2`

`289-225=OR^2`

`64=OR^2`

Taking square root on both sides.

`√(64)=OR`

`8=OR`

The val;ue of OR is 8 units.

Therefore, the correct option is A.