{"id":6784,"date":"2021-10-21T16:45:03","date_gmt":"2021-10-21T11:15:03","guid":{"rendered":"https:\/\/mathemerize.com\/?p=6784"},"modified":"2021-10-23T17:11:42","modified_gmt":"2021-10-23T11:41:42","slug":"for-what-value-of-k-does-the-line-y-x-k-touches-the-ellipse-9x2-16y2-144","status":"publish","type":"post","link":"https:\/\/mathemerize.com\/for-what-value-of-k-does-the-line-y-x-k-touches-the-ellipse-9x2-16y2-144\/","title":{"rendered":"For what value of k does the line y = x + k touches the ellipse \\(9x^2 + 16y^2\\) = 144."},"content":{"rendered":"
\\(\\because\\) Equation of ellipse is \\(9x^2 + 16y^2\\) = 144 or \\(x^2\\over 16\\) + \\({(y-3)}^2\\over 9\\) = 1<\/p>\n
comparing this with \\(x^2\\over a^2\\) + \\(y^2\\over b^2\\) = 1 then we get \\(a^2\\) = 16 and \\(b^2\\) = 9<\/p>\n
and comparing the line y = x + k with y = mx + c ; m = 1 and c = k<\/p>\n
If the line y = x + k touches the ellipse \\(9x^2 + 16y^2\\) = 144, then \\(c^2\\) = \\(a^2m^2 + b^2\\)<\/p>\n
\\(\\implies\\) \\(k^2\\) = 16 \\(\\times\\) \\(1^2\\) + 9 \\(\\implies\\) \\(k^2\\) = 25<\/p>\n
\\(\\therefore\\)\u00a0 k = \\(\\pm\\)5<\/p>\n
The foci of an ellipse are \\((\\pm 2, 0)\\) and its eccentricity is 1\/2, find its equation.<\/a><\/p>\n If the foci of a hyperbola are foci of the ellipse \\(x^2\\over 25\\) + \\(y^2\\over 9\\) = 1. If the eccentricity of the hyperbola be 2, then its equation is :<\/a><\/p>\n Find the equation of the ellipse whose axes are along the coordinate axes, vertices are \\((0, \\pm 10)\\) and eccentricity e = 4\/5.<\/a><\/p>\n Find the equation of the tangents to the ellipse \\(3x^2+4y^2\\) = 12 which are perpendicular to the line y + 2x = 4.<\/a><\/p>\n