If the equation cos4 $\theta $ + sin4 $\theta $ + $\lambda $ = 0 has real solutions for $\theta $, then $\lambda $ lies in the interval :

Question

If the equation cos⁴ $\theta $ + sin⁴ $\theta $ + $\lambda $ = 0 has real solutions for $\theta $, then $\lambda $ lies in the interval :

$\left[ { - {3 \over 2}, - {5 \over 4}} \right]$

$\left( { - {1 \over 2}, - {1 \over 4}} \right]$

$\left( { - {5 \over 4}, - 1} \right]$

$\left[ { - 1, - {1 \over 2}} \right]$

Please login to view the detailed solution steps...