Verifiying an Equation

[714.mickey]

[h=2]Verifying an Equation[/h]

cos (3x) = cos^3 (x) - 3sin^2 (x)cos(x)

I am looking to verify this equation. The underlined part is to be multiplied together. I started on the right side and factored out the cos (x), but I ran into trouble. Thanks for the help.​

 

[mmm4444bot]

Hi there. You did not show your factorization, so I don't know for certain what you're looking at.

Try using the Pythagorean trig identity for cos(x)^2, in the factored right-hand side. You should get a difference of squares.

If you need more help, please show us what you've done. :cool:

For future reference, it helps us to know specifics about phrases like "ran into trouble". Check out the post titled "Read Before Posting" for more guidelines. Cheers!