CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon


Question

Suppose $$\cos{A}$$ is given. If only one value of $$\cos { \left( \cfrac { A }{ 2 }  \right)  } $$ is possible, then $$A$$ must be


A
An odd multiple of 90o
loader
B
A multiple of 90o
loader
C
An odd multiple of 180o
loader
D
A multiple of 180o
loader

Solution

The correct option is C An odd multiple of $${ 180 }^{ o }$$
$$2\cos^{2} \dfrac {A}{2} - 1 = \cos A$$
$$\Rightarrow 2\cos^{2} \dfrac {A}{2} = \cos A + 1\Rightarrow \cos \dfrac {A}{2} = \pm \sqrt {\dfrac {1 + \cos A}{2}}$$
If one value of $$A$$ possible then $$\cos A$$ must be $$'-1'$$, therefore
$$'A'$$ must be odd multiple $$180^o$$

Mathematics

Suggest Corrections
thumbs-up
 
0


similar_icon
Similar questions
View More


similar_icon
People also searched for
View More



footer-image