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3-1.Vectors
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Two vectors $\overrightarrow a $ and $\overrightarrow b $ are at an angle of $60^o$ with each other. Their resultant makes an angle of $45^o$ with $\overrightarrow a $ . If $|\overrightarrow b | = 2\,units$ then $|\overrightarrow a |$ is:-
A
$\sqrt 3$
B
$\sqrt 3 - 1$
C
$\sqrt 3 + 1$
D
$\sqrt 3 / 2$
Solution
The vectors make $60^{\circ}$ with each other, and the resultant vector makes $45^{\circ}$ with $a$ The other angle $=15^{\circ}$ Using the side rule;
$a / \sin 15=2 / \sin 45$
$a=2 \sin 15 / \sin 45$
$a=0.732$
$ \sqrt{3}-1$
Standard 11
Physics
