1(xi)
In the given diagram, the radius of the circle with centre O is 3 cm. PA and PB are the tangents to the circle which are at right angle to each other. The length of OP is:

- (a)$\frac{3}{\sqrt{2}}$ cm
- (b)3 cm
- (c)$3\sqrt{2}$ cm
- (d)$6\sqrt{2}$ cm
Show SolutionHide Solution↓
Join OA and OP.
Given,
Radius of circle (OB) = 3 cm
PB and AP are at right angles.
We know that,
Radius and tangent at point of contact are perpendicular to each other.
OA ⊥ AP
From figure,
⇒ OA = OB = 3 cm [Radius of circle]
⇒ OB is perpendicular to PB
⇒ ∠OBP = 90°
This shows APBO is square.
OA = PB = AP = OB = 3 cm.
In right angled triangle OBP,
⇒ OP2 = OB2 + PB2
⇒ OP2 = 32 + 32
⇒ OP2 = 9 + 9
⇒ OP2 = 18
⇒ OP = $\sqrt{18}$
⇒ OP = $3\sqrt{2}$ cm.
Hence, option 3 is the correct option.