SOLUTION: Use the addition and subtraction formulas to simplify cos(x-{{{3PI/2}}}). a. cos x b. sin x c. -cos x d. -sin x

Question 73910This question is from textbook
: Use the addition and subtraction formulas to simplify cos(x-).
a. cos x
b. sin x
c. -cos x
d. -sin x
This question is from textbook

Answer by bucky(2189) (Show Source): You can put this solution on YOUR website!
Simplify cos(x-)
.
The reduction formula that you are looking for is:
.

.
For this problem and .
.
All you now have to do is to make the appropriate substitutions into the formula to get:
.

.
Now recognize that degrees. Thinking in terms of degrees may make it easier for
you to visualize that and .
.
Make these substitutions into the formula and you get:
.

.
On the right side the multiplication by zero makes the first term disappear and the multiplication
by -1 in the second term makes it become -sin(x). So the answer to this problem is:
.

.
Answer d is the correct selection
.
Hope this problem makes you aware of how the reduction formula for the cosine of the difference
between two angles works.

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