Question

which expression is equivalent to sin7pi/6?

A. sinpi/6
B. sin5pi/6
C. sin5pi/3
D. sin11pi/6

Answer 1

The answer choice is D because sin7pi/6 which it’s exact form is -1/2 the only answer choice which the same exact form is D.

Answer 2

For this case we must find an expression equivalent to:

$Sin (\frac {7 \pi} {6})$

According to the unit circle, $\frac {7 \pi} {6}$ is in the third quadrant and equals 210 degrees.

Then, we must find an expression equivalent to:

$Sin (210) = - \frac {1} {2} = - 0.5$

We have to:

$\frac{11 \pi} {6}$

It is in the fourth quadrant and is equivalent to 330 degrees, according to the unit circle.

$Sin (330) = - \frac {1} {2} = - 0.5$

Answer:

Option D