Q.

Assertion(A): sec 2θ-tan 2θ=1 for all values of θ90°.

Reason(R): sin 2θ+cos 2θ=1

1 Both A and R are true, and R is the correct explanation of A.  
2 Both A and R are true, but R is not the correct explanation of A.  
3 A is true, but R is false  
4 A is false, but R is true  

Ans.

(1)

Both Assertion and Reason are true, and the Reason is the correct explanation of the Assertion. If you divide the basic Pythagorean identity

sin 2θ+cos 2θ=1 by cos 2θ then you get 1+tan 2θ=sec 2θsec 2θ-tan 2θ=1.