The main identity you need is the double angle one for cosine:

We get

Expand the numerator to apply the identity again:




Finally, make use of the product identity for cosine:

so that ultimately,


Answer:
**********************868/14=62********************
Step-by-step explanation:
Answer:
vStep-by-step explanation:
Answer:
_ <u>3a^8-8r^3</u>
4r^3
Step-by-step explanation: