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If sinA=(3)/(5)"where "450^(@)ltAlt540^(...

If `sinA=(3)/(5)"where "450^(@)ltAlt540^(@)`,then `"cos"(A)/(2)` is equal to

A

`(1)/(sqrt(10))`

B

`-sqrt((3)/(10))`

C

`(sqrt(3))/(sqrt(10))`

D

None of the above

Text Solution

Verified by Experts

The correct Answer is:
D
`sinA=(3)/(5),450^(@)ltAlt54^(@)`
`rArr225^(@)lt(A)/(2)lt270^(@)`
`cosA=(-4)/(5)(because A" lies in Q 2")`

`therefore"cos"^(2)(A)/(2)=(1+cosA)/(2)=(1)/(10)`
`rArr"cos"(A)/(2)=(-1)/(sqrt(10))(because(A)/(2)" lies in Q 3")`
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