Question

What is the value of cosθ given that (−2, 9) is a point on the terminal side of θ ? 985√85

Answer 1

Answer:

-2√85 / 85

Step-by-step explanation:

Answer 2

Answer:

$cos\theta=\frac{-2}{\sqrt{85} }$

Step-by-step explanation:

Let's call r the distance form the origin to the point (-2,9), this distance is related with $cos\theta$ with the expression

$x=rcos\theta\\cos\theta=\frac{x}{r}$

So, we have to find r with the formula of distance and the given point:

$r=\sqrt{x^{2}+y^{2}}=\sqrt{(-2)^{2}+(9)^{2} }\\r=\sqrt{4+81}=\sqrt{85}$

Now, replacing on the first relation, we have

$cos\theta=\frac{-2}{\sqrt{85} }$

Therefore, the answer is

$cos\theta=\frac{-2}{\sqrt{85} }$

PD: choices were written wrong.