Question
Find the exact value of the expression. Do not use a calculator. cos(-(17pi )/(4))-csc(-(17pi )/(4)) Select the correct choice below and, if necessary.fill in the answer box to complete your choice. A. cos(-(17pi )/(4))-csc(-(17pi )/(4))= (Simplify your answer, including any radicals. Use integers or fractions for any numbers in the expression. B. The answer is undefined.
Solution
4.2
(360 Votos)
Zuila Maria
Elite · Tutor por 8 anos
Resposta
To find the exact value of the expression, we need to simplify the trigonometric functions.The cosine function is an even function, which means that
. Therefore, we can rewrite the expression as:
Next, let's simplify the cosecant function. The cosecant function is the reciprocal of the sine function, so
. Also, the sine function is an odd function, which means that
. Therefore, we can rewrite the expression as:
Now, let's simplify the sine function. The sine function has a period of
, which means that
for any integer
. Therefore, we can rewrite the expression as:
To find the exact value of the expression, we need to find the value of
modulo
. Since
is greater than
, we can subtract
until we get a value less than
. We get:
Therefore, we can rewrite the expression as:
The exact values of the cosine and sine functions for
are
and
, respectively. Therefore, we can substitute these values into the expression:
Simplifying further, we get:
Rationalizing the denominator, we get:
Simplifying further, we get:
Therefore, the exact value of the expression is
.So, the correct choice is A.