Question

If $P(a\cos \theta ,b\sin \theta )$ is a point on an ellipse $\frac{x^2}{a^2}+\frac{y^2}{b^2}=1$, then ' $\theta$ ' is

• A. angle of $OP$ line from positive direction of $x$-axis ( $O$ is origin)
• B. angle of $OQ$ line from positive direction of $x$-axis [when $Q$ is $(a\cos \theta ,a\sin \theta )$ ]
• C. it depends on the pont $P$
• D. none of the above

Answer 1

Answer: (B)

$P(a\cos \theta ,b\sin \theta )$, then $\theta$ is angle of a corresponding pont on auxilliary circle $x^2+y^2=a^2$ i.e., $(a\cos \theta ,a$ $\sin \theta )$