Find the angle in radian through which a pendulum swings if its length is $75\, cm$ and the tip describes an arc of length.
$21\,cm$
We know that in a circle of radius $r$ unit, if an arc of length $l$ unit subtends
An angle $\theta$ radian at the centre, then $\theta=\frac{l}{r}$
It is given that $r=75 \,cm$
Here, $l=21 \,cm$
$\theta=\frac{21}{75}$ radian
$=\frac{7}{25}$ radian
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If $\left| {\,a\,{{\sin }^2}\theta + b\sin \theta \cos \theta + c\,{{\cos }^2}\theta - \frac{1}{2}(a + c)\,} \right|\, \le \frac{1}{2}k,$ then ${k^2}$ is equal to
If $\cos \theta = \frac{1}{2}\left( {x + \frac{1}{x}} \right)$, then $\frac{1}{2}\left( {{x^2} + \frac{1}{{{x^2}}}} \right) = $
If $\alpha = 22^\circ 30',$ then $(1 + \cos \alpha )(1 + \cos 3\alpha )$ $(1 + \cos 5\alpha )(1 + \cos 7\alpha )$ equals
Find the value of $\sin 15^{\circ}$