Vector $$\overrightarrow A $$ makes equal angle with $$x,y$$ and $$z$$-axis. Value of its components in terms of magnitude of $$\overrightarrow A $$ will be
A.
$$\frac{A}{{\sqrt 3 }}$$
B.
$$\frac{A}{{\sqrt 2 }}$$
C.
$$\sqrt 3 A$$
D.
$$\frac{{\sqrt 3 }}{A}$$
Answer :
$$\frac{A}{{\sqrt 3 }}$$
Solution :
Let the components of $$\overrightarrow A $$ make angles $$\alpha ,\beta $$ and $$\gamma $$ with $$x,y$$ and $$z$$-axis respectively then $$\alpha = \beta = \gamma $$ and
$$\eqalign{
& {\cos ^2}\alpha + {\cos ^2}\beta + {\cos ^2}\gamma = 1 \cr
& \Rightarrow 3{\cos ^2}\alpha = 1 \Rightarrow \cos \alpha = \frac{1}{{\sqrt 3 }} \cr
& \therefore {A_x} = {A_y} = {A_z} = A\cos \alpha = \frac{A}{{\sqrt 3 }} \cr} $$
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