A) \[1+2{{\sin }^{2}}\left( \frac{\theta }{2} \right)\]
B) \[2{{\cos }^{2}}\theta -1\]
C) \[1-2{{\sin }^{2}}\left( \frac{\theta }{2} \right)\]
D) \[1+2{{\cos }^{2}}\theta \]
Correct Answer: B
Solution :
\[{{\cos }^{4}}\theta -{{\sin }^{4}}\theta \] \[=({{\cos }^{2}}\theta -{{\sin }^{2}}\theta )({{\cos }^{2}}\theta +{{\sin }^{2}}\theta )\] \[=\cos 2\theta =2{{\cos }^{2}}\theta -1\]
You need to login to perform this action.
You will be redirected in
3 sec
