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If the normal at any point `P`on theellipse `(x^2)/(a^2)+(y^2)/(b^2)=1`meets theaxes at `Ga n dg,`respectively, then find the raio `P G: Pgdot` |
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Answer» Let `P( a cos theta, b sin theta)` be a point on the ellipse `(x^(2))/(a^(2))+(y^(2))/(b^(2))=1` Then the quation of the normal at P is `ax sec theta-"by cosec" theta=a^(2)-b^(2)` It meets the axe at `G((a^(2)-b^(2))/(a)cos, theta,0)and g (0,-(a^(2)-b^(2))/(b) sin theta)` `:. PG^(2)=(acos theta-(a^(2)-b^(2))/(a)costheta)^(2)+b^(2)sin^(2)theta=(b^(2))/(a^(2))(b^(2) cos^(2)theta +a^(2)sin^(2)theta)` and `Pg^(2)=(a^(2))/(b^(2))(b^(2)cos^(2)theta +a^(2)sin^(2)theta)` `:. PG ,Pg=b^(2):a^(2)` |
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