Unproctored Placement Assessment
Question 11

Let [tex]$(-5, -7)$[/tex] be a point on the terminal side of [tex]$\theta$[/tex].
Find the exact values of [tex]$\cos \theta, \csc \theta$[/tex], and [tex]$\tan \theta$[/tex].

[tex]\[ \cos \theta = \frac{5}{\sqrt{74}} \][/tex]



Answer :

Let's analyze the given point [tex]\((-5, -7)\)[/tex] which lies on the terminal side of angle [tex]\(\theta\)[/tex].

1. Calculate the hypotenuse [tex]\( r \)[/tex]:

The hypotenuse [tex]\( r \)[/tex] can be found using the Pythagorean Theorem:
[tex]\[ r = \sqrt{x^2 + y^2} \][/tex]

With [tex]\( x = -5 \)[/tex] and [tex]\( y = -7 \)[/tex]:
[tex]\[ r = \sqrt{(-5)^2 + (-7)^2} = \sqrt{25 + 49} = \sqrt{74} \][/tex]

2. Calculate [tex]\( \cos \theta \)[/tex]:

The cosine of angle [tex]\(\theta\)[/tex] is given by:
[tex]\[ \cos \theta = \frac{x}{r} \][/tex]

Plugging in [tex]\( x = -5 \)[/tex] and [tex]\( r = \sqrt{74} \)[/tex]:
[tex]\[ \cos \theta = \frac{-5}{\sqrt{74}} \][/tex]

Simplify if necessary, but we already see:
[tex]\[ \cos \theta \approx -0.5812381937190965 \][/tex]

3. Calculate [tex]\( \csc \theta \)[/tex]:

The cosecant [tex]\( \csc \theta \)[/tex] is the reciprocal of the sine [tex]\( \sin \theta \)[/tex]:
[tex]\[ \csc \theta = \frac{r}{y} \][/tex]

We know [tex]\( r = \sqrt{74} \)[/tex] and [tex]\( y = -7 \)[/tex]:
[tex]\[ \csc \theta = \frac{\sqrt{74}}{-7} \][/tex]

Again, simplify:
[tex]\[ \csc \theta \approx -1.228903609577518 \][/tex]

4. Calculate [tex]\( \tan \theta \)[/tex]:

The tangent of angle [tex]\(\theta\)[/tex] is given by:
[tex]\[ \tan \theta = \frac{y}{x} \][/tex]

With [tex]\( y = -7 \)[/tex] and [tex]\( x = -5 \)[/tex]:
[tex]\[ \tan \theta = \frac{-7}{-5} = \frac{7}{5} \][/tex]

Simplifying gives us:
[tex]\[ \tan \theta = 1.4 \][/tex]

So the final values are:

- [tex]\( \cos \theta \approx -0.5812381937190965 \)[/tex]
- [tex]\( \csc \theta \approx -1.228903609577518 \)[/tex]
- [tex]\( \tan \theta = 1.4 \)[/tex]