Class 11

Math

Algebra

Sequences and Series

If $sinx+cosx=y+y1 ,xϵ[0,π]$ and $y>0$, then-

- $x=π/4$
- $x=2π $
- $x=6π $
- $x=3π/4$

$y+y1 ≥2$ ...(i)

$1+sin2x=y+y1 $ ...(ii)

From (i) and (ii), we get

$sin2x≥1$

$⇒sin2x=1$

$⇒2x=2π $

$⇒x=4π $

Hence, option 'A' is correct.