Question

cos 1620°
1
0
-1
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15 multiple choice 1 point
evaluate the trigonometric function of the given quadrantal angle.
sin (-450°)
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0
1
-1

Explanation:

Step1: Find the coterminal angle

Coterminal angles are angles that have the same initial and terminal sides.
To find a coterminal angle of \(\theta=- 450^{\circ}\), we use the formula \(\theta + 360^{\circ}n\), where \(n\) is an integer.
Let \(n = 2\), then \(\theta+360^{\circ}\times2=-450^{\circ}+720^{\circ}=270^{\circ}\)

Step2: Evaluate the sine function

We know that for the unit - circle, \(\sin\alpha=y\) - coordinate of the point on the unit - circle corresponding to the angle \(\alpha\).
For \(\alpha = 270^{\circ}\), the point on the unit - circle is \((0,-1)\)

Answer:

\(-1\)