(3) Put x = a tan θ Then dx = a sec2 θ dθ Therefore,      
2
2
dx
x
+a
∫
 = 
2
2
2
2
θ
θ
secθ
tan
a
d
a
+a
∫
=
1
1
1
1
θ
θ
C
tan
C
– x
d
a
a
a
a
=
+
=
+
∫
(4) Let x = a secθ Then dx = a secθ tan θ d θ