am i dumb, why cant i do this (1 Viewer)

[yashbb]

prove qs

 

[011235]

c)








b)








Useful things to remember:

 

[CM_Tutor]

In a case like (c), where it may not be obvious what to do, it sometimes helps to examine LHS - RHS and see if you can get 0, then note that if LHS - RHS = 0 then it necessarily follows that LHS - RHS. A good example like this is the proof that

​

 

[CM_Tutor]

Also, note that these identities can be linked to solving equations. For example, solving



is potentially easier by rewriting as



and substituting with the identity to form



which can be immediately simplified to

 

[yashbb]

Also, note that these identities can be linked to solving equations. For example, solving



is potentially easier by rewriting as



and substituting with the identity to form



which can be immediately simplified to

can i ask how to this one then?

 

[CM_Tutor]

Expand LHS using the double angle formula. To start with...

​

Similarly, you should find that

​

So:

​