c2 circles

a) show that the line y=3x + 10 is a tangent to the circle x^2 + y^2 = 10

b) draw a sketch showing the line and the circle above and hence write down the equation of another line 'passing through the point (0,10)' which is also a tangent to the circle x^2 + y^2 =10


thank you so much for any help

Well, substitute the equation of the line into the circle and consider the nature of the resulting quadratic.

Hint:

It's a tangent if

$b^2 = 4ac$

sorry I got part a) but for b)? thanks

Hint:

The line can be horizontal, you know

Hint:

The line can be horizontal, you know

Not sure that helps

hmmm... still not to sure ..

hmmm... still not to sure ..

do you mind explaining it, tenofthem? thanks .

(0,10) is at the top of the circle, right?

Use symmetry

I assume that you have found where the first line met the circle ... symmetry will tell you where this new line meets the circle

Then you have 2 points, therefore an equation

nope I haven't found where the first line meets the circle

No, it isn't

well it is not much beyond the work you did for (a)

sub in when x =0 to find y?

no

didn't you have a quadratic with a single solution as part of (a)

no

didn't you have a quadratic with a single solution as part of (a)

sub in when x =0 to find y?