Prove that
tan
-
1
2
a
b
a
2
-
b
2
+
tan
-
1
2
x
y
x
2
-
y
2
=
tan
-
1
2
α
β
α
2
-
β
2
where
α
=
a
x</
Matching exercise
Match the items on the right to the items on the left.
Check
OK
Step 1
Step 2
Step 3
Step 4
Step 5
Step 6