Answer:
1)
2)0
Step-by-step explanation:
for part 1:
Given cos(x) - cos^3(x)
= cos(x) (1- cos^2(x))
Using the identity 
= cos(x)sin^2(x)
for part 2:
given
=
Using the identity cos(a)cos(b) + sin(a)sin(b)= cos(a-b)
=
=
=
=0!
Answer:
I don't recognize this problem, please make sure the input is complete.
Step-by-step explanation:
it that the full problem?
Answer:
Step-by-step explanation:
X = 90°