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If AOB is a diameter of the circle and ...

If AOB is a diameter of the circle and AC=BC, then `angle CAB` is equal to

A

`30^(@)`

B

`45^(@)`

C

`60^(@)`

D

`90^(@)`

Text Solution

Verified by Experts

The correct Answer is:
B

We know that, diameter subtends a right angle to the circle.
`:. angleBCA=90^(@)...(i)`
`"Given",AC=BC`
`rArrangleABC=angleCAB ...(ii)`
[angles opposite to equal sides are equal]

In `DeltaABC, angleCAB+angleABC+angleBCA=180^(@)`
[by angle sum property of a triangle]
`rArr angleCAB+angleCAB+angle90^(@)=180^(@)["form Eqs. (i) and (ii)"]`
`rArr 2angleCAB=180^(@)-90^(@)`
`rArr angle CAB=(90^(@))/2`
`:.angleCAB=45^(@)`
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