The maximum distance from origin of a point on the curve $x=a \sin t-b \sin \left(\frac{a t}{b}\right)$ $y=a…

The maximum distance from origin of a point on the curve $x=a \sin t-b \sin \left(\frac{a t}{b}\right)$ $y=a \cos t-b \cos \left(\frac{a t}{b}\right)$, both $a, b>0$ is
  1. a - b
  2. a + b
  3. $\sqrt{a^2+b^2}$
  4. $\sqrt{a^2-b^2}$

Solution

Distance of origin from $(x, y)=\sqrt{x^2+y^2}$ $ =\sqrt{a^2+b^2-2 a b \cos \left(t-\frac{a t}{b}\right)}=\sqrt{a^2+b^2-2 a b}\left[\because \max \cdot \cos \left(t-\frac{a t}{b}\right)=1\right]=a-b $

Asked in: JEE Main 2002

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