How would we solve this?

[round grove]

1. Ask your question and show the work you've done so far. If you've posted a screenshot of a question, specify which part you need help with.
2. Wait patiently for a helper to come along.
3. Once someone helps you, say thank you and close the thread with:

   +close
   

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6. If you're happy with the help you got here, and the server overall, you can contribute financially as well:

[dawn jetty]

You can rewrite the equation as $$\cos 5 \theta \cos 3\theta=\cos \theta \cos 7\theta$$ Now, apply the given identity on both sides.

[obtuse sphinx]

Civil Service Pigeon

[violet smelt]

when you say “$$” you mean what exactly?

[dawn jetty]

That's just to get @obtuse sphinx to compile the latex

[dawn jetty]

read this

[violet smelt]

ah ok

[violet smelt]

ye

my brain stopped working

how do we apply the given identities 😭

[dawn jetty]

eh I kinda lied a bit

use product to sum first

[violet smelt]

so cos a is cos 5 theta

and cos b is cos 3 theta

correct?

[dawn jetty]

yeah

[violet smelt]

alright done, now what do we do

same thing with the other side right?

[dawn jetty]

yeah

[violet smelt]

done, now what do we do

[dawn jetty]

what do you have now

[violet smelt]

i’ve just put everything into the formula

[dawn jetty]

I mean ...

after you used the formula

what do you get as the result on both sides

[violet smelt]

alright one sec

[dawn jetty]

hello?

welp uh

alright ig

bye