Step-by-step explanation:
θ is in quadrant IV, so:
sin θ < 0
cos θ > 0
tan θ = sin θ / cos θ < 0
csc θ = 1 / sin θ < 0
sec θ = 1 / cos θ > 0
Without doing any calculations, we can see only the third option fits (in the second option, sin θ / cos θ = -9/18, not -18/9. In the fourth option, csc θ and sec θ are switched).
Let's go ahead and calculate the values. There are several ways to solve this. One way is to use Pythagorean identities (ex., 1 + cot²θ = csc²θ). Another way is to simply draw a triangle in the fourth quadrant.
cot θ = 1 / tan θ, and tan θ = opposite / adjacent. So cot θ = adjacent / opposite. If we draw a triangle with angle θ, where the adjacent side is 9 and the opposite side is -18, then we can use Pythagorean theorem to find the hypotenuse:
c² = a² + b²
c² = (9)² + (-18)²
c = √405
Therefore:
sin θ = -18 / √405
cos θ = 9 / √405
csc θ = √405 / 18
sec θ = √405 / 9
tan θ = -18/9
