AP EAMCET2015MathematicsTrigonometric Ratios & Identities
If + =p and + =q , then q (p^2-1 ) is equal to
Options
- A1 2
- B2
- C1
- D3
Correct answer
B. 2
Step-by-step solution
We have given, From Eq. (i) aligned & ( + )^2=p^2 & ^2 + ^2 +2 =p^2 & [ ^2 + ^2 and 2 =2 ] & 1+ 2 =p^2 aligned From Eq. (ii), + =q aligned & + 1 =q ^2 +1 =q & ^2 +1 2 = q 2 [ cosec 2 = ^2 +1 2 ] & cosec 2 = q 2 & 2 = 2 q aligned p^2-1= 2 q [from eq. (iii)] q (p^2-1 )=2