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3.Trigonometrical Ratios, Functions and Identities
easy
Find the angle in radian through which a pendulum swings if its length is $75\, cm$ and the tip describes an arc of length.
$15\,cm$
A
$\frac{1}{5}$
B
$\frac{1}{5}$
C
$\frac{1}{5}$
D
$\frac{1}{5}$
Solution
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, $l=15\, cm$
$\theta=\frac{15}{75}$ radian
$=\frac{1}{5}$ radian
Standard 11
Mathematics