Answer:
When proving identities, the answer is in the explanation.
Step-by-step explanation:

I have two terms in this denominator here.
I also know that
by Pythagorean Identity.
So I don't know how comfortable you are with multiplying this denominator's conjugate on top and bottom here but that is exactly what I would do here. There will be other problems will you have to do this.

Big note here: When multiplying conjugates all you have to do is multiply fist and last. You do not need to do the whole foil. That is when you are multiplying something like
, the result is just
.
Let's do that here with our problem in the denominator.





In that last step, I apply the Pythagorean Identity I mentioned way above.
Now You have a factor of cos(y) on top and bottom, so you can cancel them out. What we are really saying is that cos(y)/cos(y)=1.

This is the desired result.
We are done.
Answer:
-4y^3-16y^2+52y hope this helps!!
Step-by-step explanation:
Simplify it
I couldn’t find you on Inst. M’I missing something?
Answer:
The length of BC is 17
Step-by-step explanation:
When we construct a triangle with the data, we will end up a isosceles triangle.
In a isosceles triangle , we know that tow angles and two sides are equal
The questions states that

Then sides AC and AB are also equal
On equation their values
2X - 8 = X+9
2X = X + 9 +8
2X = X + 17
2X - X = 17
X = 17
The length of BC = X = 17