–1
1
sin
1
sin
cot
2
1
sin
1
sin
x
x
x
x
x


+
+
−
=




+
−
−


, 
0, 4
x
π


∈



10 –1
–1
1
1
1
tan
cos
4
2
1
1
x
x
x
x
x


+
−
−
=π
−




+
+
−


, 
1
1
2
x
−
≤
≤  [Hint: Put x = cos 2θ]
Solve the following equations:
11 2tan–1 (cos x) = tan–1 (2 cosec x)
12 –1
–1
1
1
tan
tan
,(
0)
1
2
x
x x
x
−
=
>
+
13