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Grade 11Algebra

show that the tangents to the parabola y^2=4ax at the ends f the latus rectum meet at its directrix

Profile image of Nishtha Gahlot
8 Years agoGrade 11
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1 Answer

Profile image of sahil
8 Years ago
Sol:take the parabola as y^2=4ax now cordinates of its end of latus rectum are (a,2a) ; (a,-2a).Now tangent at any point (x`,y`) on parabola is yy`=2a(x+x`).Tangent at point (a,2a) is 2ay=2ax+2a^2 and at (a,-2a) is -2ay=2ax+2a^2 .Solve this linear equation in two unknown to get point of intersection of tangent y=0 and x=-a ;so the point of intersection is (-a,0) and it clearly lie on directrix. If it was helpful pleaseapprove my answer.