Proving a trig identity

A

Antroph1c

New member
Joined
Jan 22, 2022
Messages
13
Hello, I am unsure as to how to prove this trig identity, (If you can show the full working to obtain the answer, I'll very much appreciate it ?)
 

Attachments

  • Untitled.png
    Untitled.png
    98.5 KB · Views: 8
No-one here will show you the full working, but we will help YOU prove the identity.

First of all, what are the formula you have been instructed to use?
 
That's the formula for cos (A+/-B). You are asked to use the formula for cos A +/- cos B. Can you see the difference?
 
OH, i didnt notice that for the longest time, Im so sorry for bothering you, thank you for your time ?
 
You must log in or register to reply here.
Top