Edexcel Mathematics October 2020 · Paper 2 · Question 14 · ExamRizz

ExamRizzEdexcel MathematicsMathematics

October 2020 · Paper 2 · Question 14 · 7 marks

14. A circle C with radius r ● lies only in the 1st quadrant ● touches the x-axis and touches the y-axis The line l has equation 2x + y = 12 (a) Show that the x coordinates of the points of intersection of l with C satisfy 5x 2 + (2r − 48 ) x + (r 2 − 24r + 144 ) = 0 (3) Given also that l is a tangent to C, (b) find the two possible values of r, giving your answers as fully simplified surds. (4) 43 44 45

Lesson: Equations of a Straight Line