29Ans C..
The circles on focal radii of a parabola as diameter touch
A The tangent at the vertex
B The axis
C The directrix
D None of above
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6 Answers
29latus rectum is also a focal radii so a circle drawn using the the latus rectum will have radius 2a so it will pass through (0,-a) ..if the eqn of parabola is y2 = 4ax
29oops..sry latus rectum cannot be taken as focal radii..maybe half of latus rectum can be taken as a focal radii...so Ans will be A
1
Ya the ans will be A...Take a parabola y2=4ax,here the focal radii is 4a now a circle is drawn on focal radii as diameter ie with radius 2a hence this circle passes thru the origin with (2a,0) as centre so it will touch the tangent to the parabola at the origin(0,0) and this tangent is the Y axis for y2=4ax...Did u get it??