Quantitative Aptitude Ques 322
Question: The value of $ (\cos 0{}^\circ +\sin 45{}^\circ +\sin 30{}^\circ ) $ $ (sin90{}^\circ -cos45{}^\circ +\cos 60{}^\circ ) $ is
Options:
A) $ \frac{3}{2} $
B) $ \frac{7}{4} $
C) $ \frac{5}{4} $
D) $ \frac{3}{4} $
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Answer:
Correct Answer: B
Solution:
- $ (\cos 0{}^\circ -\sin 45{}^\circ +\sin 30{}^\circ ) $
$ (\sin 90{}^\circ -\cos 45{}^\circ +\cos 60{}^\circ ) $
$ =( 1+\frac{1}{\sqrt{2}}+\frac{1}{2} )( 1-\frac{1}{\sqrt{2}}+\frac{1}{2} ) $
$ =( \frac{3}{2}+\frac{1}{\sqrt{2}} )( \frac{3}{2}-\frac{1}{\sqrt{2}} ) $
$ ={{( \frac{3}{2} )}^{2}}-{{( \frac{1}{\sqrt{2}} )}^{2}}=\frac{9}{4}-\frac{1}{2}=\frac{9-2}{4}=\frac{7}{4} $