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

Answer:

Option A.

Step-by-step 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.

$RB=\dfrac{AB}{2}$

$RB=\dfrac{30}{2}$

$RB=15$

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.

$\sqrt{64}=OR$

$8=OR$

The val;ue of OR is 8 units.

Therefore, the correct option is A.