Ineed assistance in this multipart question. this question is quite difficult for me and would gladly appreciate it if someone would me solve this.

6. Expand the left side:

Recall the Pythagorean identity,

which leaves us with

Recall the angle sum formula for cosine:

which gets us to where we need to be:

and we're done.

7. A. The formulas you need are

This gives

7. B. Solving for gives

which holds for

where is any integer.

7. C. Factorize as

From here, we have

which hold for

where is any integer.

1^3 + 2^3 + 3^3 +4^3 = (1+2+3+4)^2

step-by-step explanation:

i am only able to answer the first part. i am not sure about the second part. sorry