[Index]
Introduction
Essence
Memorizing
Understanding
Summarizing
Examples
Example 1
Example 2
Example 3
Example 4
Example 5
Example 6
Example 7
Example 8
General ideas
Exercises
Final thoughts
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Example 5--Page 2
This time we don't multiply the left by 
. Instead, we multiply it by 
.
Now, we want the first factor to be 
. To do so, we need change functions 
to 
.
Try to simplify the terms on the top of first factor. If we use the Product
to Sum formulas to convert them to addition, we'll get 
,
from ,
;
and ,
from ,
,
which yields like terms of 
.
We want the first factor to be .
Because the right side of the identity doesn't have a denominator,
so we need to cancel 
.
By using the Sum to Product formulas
on the top of first factor, we get:
Then we use a Double Angle formula to convert
to 
and canceling 
.
We have:
