1.

The value of `(1-tan^2 1 5^(@))/(1+tan^2 1 5^(@))` isA. 1B. `sqrt(3)`C. `(sqrt(3))/(2)`D. 2

Answer» Correct Answer - 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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