NDA2011MathematicsTrigonometric Ratios & IdentitiesActual
If A - B =x and B - A =y , then what is ( A - B ) equal to?
Options
- A1 y - 1 x
- B1 x - 1 y
- C1 x + 1 y
- D- 1 x - 1 y
Correct answer
C. 1 x + 1 y
Step-by-step solution
aligned & A - B =x & ~A ~A - B B =x & ( ~A - B ) A B =x aligned ( A - B )=x ~A ~B (i) aligned & B - A =y & ~B ~B - A A =y aligned ( A - B )=y ~A ~B ...(ii) From (i) and (ii) x ~A ~B =y ~A ~B aligned & ( A - B )= ( A - B ) ( A - B ) &= A B + A B x ~A ~B & [ x ~A ~B =y ~A ~B ] aligned aligned & = 1 x + A B x ~A ~B & = 1 x + A B y ~A ~B & = 1 x + 1 y aligned