If [tex]\sec \theta = -7.3[/tex], find [tex]\sin \left(\theta - \frac{\pi}{2}\right)[/tex].

A. [tex]-0.14[/tex]
B. [tex]-7.3[/tex]
C. [tex]7.3[/tex]
D. [tex]0.14[/tex]



Answer :

Given [tex]\(\sec \theta = -7.3\)[/tex], we need to find [tex]\(\sin \left(\theta - \frac{\pi}{2} \right)\)[/tex].

First, recall that [tex]\(\sec \theta = \frac{1}{\cos \theta}\)[/tex]. This means we can express [tex]\(\cos \theta\)[/tex] in terms of [tex]\(\sec \theta\)[/tex]:
[tex]\[ \cos \theta = \frac{1}{\sec \theta} = \frac{1}{-7.3} \approx -0.136986301369863 \][/tex]

Next, we use the trigonometric identity for the sine of a shifted angle:
[tex]\[ \sin \left(\theta - \frac{\pi}{2} \right) = -\cos \theta \][/tex]

Substitute [tex]\(\cos \theta\)[/tex] into the identity:
[tex]\[ \sin \left(\theta - \frac{\pi}{2} \right) = -(-0.136986301369863) = 0.136986301369863 \][/tex]

Thus, the value of [tex]\(\sin \left(\theta - \frac{\pi}{2} \right)\)[/tex] is approximately [tex]\(0.14\)[/tex]. Therefore, the correct answer is:
[tex]\[ 0.14 \][/tex]