solve (cos theta - cos theta)^2 + (cos theta + cos theta)^2

Question

anonymous · Answer

@amistre64  could help explain this to me? i think it might be cos^2theta but im not entirely sure

amistre64 · Answer

the word 'solve' is rather vague ... what is it we are wanting to do?

amistre64 · Answer

in general tho

(a+b)^2 = a^2 + b^2 +2ab
(a-b)^2 = a^2 + b^2 -2ab

adding them together just gets us:  2a^2 + 2b^2

anonymous · Answer

well, its asking us to solve and these are my options

sin^2 theta
4cos^2theta
8
cos^2theta

amistre64 · Answer

then what can we conclude?

amistre64 · Answer

since a=b ... 

(a-a)^2 + (a+a)^2 
   0             2a

what is (2a)^2

anonymous · Answer

iim not sure, like i did this:

(cos theta-cos theta)^2 + (cos theta+cos theta)^2
(0)^2 + (cos theta 2) ^2
0+(cos theta 2 ) ^2
(cos theta 2 )^2
4cos^2 

is it the second option?

amistre64 · Answer

4 cos^2 is fine

anonymous · Answer

really? you sure? i doubt myself lol

amistre64 · Answer

typing out theta is not required ,  cos(t) works all the same

anonymous · Answer

ohh kk
so my final answer would be my second option , correct? just to be sure

anonymous · Answer

@amistre64

amistre64 · Answer

thats what we determined yes.  restating it over and over again neither strengthens nor diminishes that fact.

anonymous · Answer

ok thank you very much for helping me out :-)

amistre64 · Answer

good luck

anonymous · Answer

thanks