Let f(x)=sin23x−cos22x and g(x)=1+12tan−1|x|. Then the number of values of x in the interval [−10π, 8π] satisfying the equation f(x)=sgn(g(x)) is _____.
g(x)=12tan−1|x|+1
or sgn(g(x))=1 or sin23x−cos22x=1
or sin23x=1+cos22x
which is possible if sin x = 1 and cos x = 0. Therefore,
sinx=1,x=2nπ+π2
Hence, −10π≤2nπ+π2≤8π or −214≤n≤154
or −5≤n≤3
Hence, number of values of x = 9.