A few ways. you can enter it into a calculator for one, but the easiest way would be to reference a unit circle and look for an ordered pair where sin (the y value), is equal to -1/2
on a unit circle, the sin value is -1/2 at 7pi/6 and 11pi/6
because sin is the y value, it will additionally be in the quadrants III or IV based on the fact that (-1/2) as a sin value IS a negative and would have to be found in a quadrant in which sin is negative (the lower half of a coordinate plane, in this case)
Answer:

Step-by-step explanation:
Given
sinΘ =
= 
Then the hypotenuse = 5 and one leg of the right triangle is 3
Using Pythagoras' identity to find the second leg (x)
x² + 3² = 5²
x² + 9 = 25 ( subtract 9 from both sides )
x² = 16 ⇒ x = 4
cosΘ =
= 
Answer:
I believe it is 6.
Step-by-step explanation:
Answer:
(-b-81)/6=a
Step-by-step explanation:
3b−2a-17 = 4a+4b+64
3b-4b-17-64=4a+2a
-b-81=6a
(-b-81)/6=a