Option A

<em><u>Solution:</u></em>
Given that we have to rewrite with only sin x and cos x
Given is cos 3x

We know that,

Therefore,
---- eqn 1
We know that,


Substituting these values in eqn 1
-------- eqn 2
We know that,

Applying this in above eqn 2, we get



Therefore,

Option A is correct
The value of x is usually 1, most of the time x is just used as a place holder
Answer:
9
Step-by-step explanation:
Answer:
not sure
Step-by-step explanation:
hope it helps and use brainly it never lies
Answer:
A, B and C
Step-by-step explanation:
A. Adding another researcher to provide ratings will make the study less biased.
B. A quiz or exam will show which students have a better understanding of the math material. Better quiz or exam results show that the site is more effective for a student with or without the supplemental instruction.
C. Having a greater sample size is better because a greater scope of students is covered. Different students have different abilities and learning preferences.