Do not understand at all: (1-cos u)(1 + cos U)/ cos^2u= tan^2u

[ararod15]

okay so this problem (1-cos u)(1 + cos U)/ cos^2u= tan^2u....totally confuses me. I have no idea where to start. I do know that it's already factored for me but from there on I have no idea. Someone please help .. thank you

 

[stapel]

this problem:

. . .(1-cos u)(1 + cos U)/ cos^2u= tan^2u

....totally confuses me.

Are there really two variables (namely, "u" and "U"), or is there maybe just one? Is the equation as follows?

. . . . .\(\displaystyle \dfrac{(1\, -\, \cos(u))\, (1\, +\, \cos(u))}{\cos^2(u)}\, =\, \tan^2(u)\)

I have no idea where to start.

Unfortunately, lacking instructions, there is no way for anybody to know "where to start".

Please consult with your instructor regarding the missing information. Then, if you get stuck after attempting to follow those instructions, please reply with a clear listing of your thoughts and efforts so far. Thank you!

 

[Deleted member 4993]

okay so this problem (1-cos u)(1 + cos U)/ cos^2u= tan^2u....totally confuses me. I have no idea where to start. I do know that it's already factored for me but from there on I have no idea. Someone please help .. thank you

Hint:

(a+b)(a-b) = a² - b² and

sin²(x) + cos²(x) = 1