Evaluate :

`Sec^2( 20^(@ ) ) - tan^2( 20^(@ ))`

1 ) -1
2 ) 1
3 ) -2
4 ) 2

sec ^ (4) A (1-sin ^ (4) A) -2tan ^ (2) A = 1

Evaluate : tan^(2) ("sec"^(-1)3) + cot^(2) ("cosec^(-1) 4) .

Evaluate the following : tan^(2) ( sec^(-1) 2) + cot^(2) ( cosec^(-1) 3) .

Evaluate 2tan^(-1)(1/2)+tan^(-1)(1/4)

sec^(-1)((1+tan^(2)x)/(1-tan^(2)x))

Find the value of tan^(6)20^(@)-33tan^(4)20^(@)+27tan^(2)20^(@)-1

Evaluate: tan ^ (- 1) 1 + cos ^ (- 1) ((1) / (2)) + sin ^ (- 1) (- (1) / (2)) + tan ^ (- 1) ( -sqrt (3)) - sec ^ (- 1) (- 2) + cos ec ^ (- 1) ((2) / (sqrt (3)))

Prove that: sec^4A(1-sin^4A) -2 tan^2A=1 .

sec^(2) ( tan^(-1)2) + cosec^(2) ( cot^(-1)3) =