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Tangents and circles.

Morning everyone,

I've got this question and I'm just wondering if I could run it past someone?

'The line y=mx is tangent to circle x2+y2−10y+16=0x^2+y^2-10y+16=0 a) find the 2 possible values of M (I've done this part and get plus or minus (4/3).

This is the part I'm unsure about:
'The tangents meet the circle at points A & B. Find the length of AB"

OK, so do I substitute my found values of M into a simultaneous equation, to get the 2 points of intersection? Then, when I have the 2 points of intersection, do I use Pythagorus to calculate the distance?
Reply 1
Avatar for TenOfThem
TenOfThem
18
Original post by gavinlee
when I have the 2 points of intersection, do I use Pythagorus to calculate the distance?


Yes

though ... now I have the answers ... Pythagoras is not needed
(edited 11 years ago)
Reply 2
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gavinlee
OP
Original post by TenOfThem
Yes

though ... now I have the answers ... Pythagoras is not needed



OK thanks, is it just because it's a straight line?
Reply 3
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TenOfThem
18
Original post by gavinlee
OK thanks, is it just because it's a straight line?


yes ... though it was always going to be a straight line ... what you mean is a vertical line
Reply 4
Avatar for gavinlee
gavinlee
OP
Hi, just looking again at this one. As there are 2 values for m (+/- 4/3) Should I do 2 quadratics, substituting each value of m into a different quadratic? As the answers to the quadratic will also be +/- that would give me 4 solutions!?

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