Math, asked by Zero3992, 11 months ago

Prove that the intercept of a tangent of a circle between the two parallel tangents of 10th

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Answered by arc555
0
Given: XY and X'Y' at are two parallel tangents to the circle wth centre O and AB is the tangent at the point C,which intersects XY at A and X'Y' at B.

To prove: ∠AOB = 90º .

Construction: Join OC.

Proof: In ΔOPA and ΔOCA

OP = OC (Radii )

AP = AC (Tangents from point A)

AO = AO (Common )

ΔOPA ≅ ΔOCA (By SSS criterion)

Therefore, ∠POA = ∠COA .... (1) (By C.P.C.T)

Similarly , ΔOQB ≅ ΔOCB

∠QOB = ∠COB .......(2)

POQ is a diameter of the circle.

Hence, it is a straight line.

Therefore,

∠POA + ∠COA + ∠COB + ∠QOB = 180°

From equations (1) and (2), it can be observed that ,

2∠COA + 2∠COB = 180° ∴ ∠COA + ∠COB = 90° ∴ ∠AOB = 90°.

I hope this would help you.
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