Q. Number of integral values of $k$ for which the equation $4 \cos ^{-1}(-| x |)= k$ has exactly two solutions, is
Inverse Trigonometric Functions
Solution:
Graph of $y=4 \cos ^{-1}(-|x|)$
From the graph it is
Clear that $k \in(2 \pi, 4 \pi]$
$\therefore$ integral values of $k$ are $7,8,9,10,11,12$
