just been revising and I have came across this question but don't know how to solve it.
This question is part d of the question (with 3 sub-parts to it)
I have already found the centre of the circle and the radius on the previous parts of the question. Center (-7,5), r=5 but dont know if this comes in use to this part of the question.
The question being
A line has the equation y=kx+6, where k is a constant.
i) show that x-coordinates of any point of intersection of the line and the circle satisfy this equation (k^2+1)x^2+2(k+7)x+25=0.
ii) The equation (the one above) has equal roots. Show that 12k^2-7k-12=0
iii) Hence find the values of k for which the line is a tangent to the circle
Could you please help me?
Thanks in advance