Trigonometric Identities Question 361
Question: $ \frac{1}{4}[ \sqrt{3}\cos 23{}^\circ -\sin 23{}^\circ ]= $
Options:
A) $ \cos 43{}^\circ $
B) $ \cos 7{}^\circ $
C) $ \cos 53{}^\circ $
D) None of these
Show Answer
Answer:
Correct Answer: D
Solution:
$ \frac{1}{4}{\sqrt{3}\cos 23^{o}-\sin 23^{o}} $ $ =\frac{1}{2}{\cos 30^{o}\cos 23^{o}-\sin 30^{o}\sin 23^{o}} $ $ =\frac{1}{2},\cos ,(30^{o}+23^{o})=\frac{1}{2},\cos ,53^{o}. $
BETA
