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If the line y cos alpha=x sin alpha+a co...

If the line `y cos alpha=x sin alpha+a cos alpha` be a tangtnt to the circle `x^(2)+y^(2)=a^(2)` then

A

`sin ^(2) alpha=1`

B

`cos ^(2) alpha=1`

C

`sin ^(2) alpha=a^(2)`

D

`cos ^(2) alpha=a^(2)`

Text Solution

Verified by Experts

The correct Answer is:
B
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