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The value of (1-tan^2 1 5^(@))/(1+tan^2...

The value of `(1-tan^2 1 5^(@))/(1+tan^2 1 5^(@))` is

A

1

B

`sqrt(3)`

C

`(sqrt(3))/(2)`

D

2

Text Solution

Verified by Experts

The correct Answer is:
C
Given expression, `(1-tan^(2)15^(@))/(1+tan^(2)15^(@))`
Let `" "theta=15^(@)`
We know that, `" " cos2theta=(1-tan^(2)theta)/(1+tan^(2)theta)`
`" " cos2theta=(1-tan^(2)theta)/(1+tan^(2)theta)`
`rArr" "(1-tan^(2)15^(@))/(1+tan^(2)15^(@))=(sqrt(3))/(2)` `" "[becausecos30^(@)=(sqrt(3))/(2)]`
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