Help with this maths question please!

[engstrom0304]

Hey guys..

So im a little stuck...

heres the question:

A tangent is drawn from point (6,4) to the circle (x-1)^2 + (y-3)^2 = 9 .
Find the length of the tangent...

Now ive been taught all the equations i need to know i think...

So far ive just found the centre of the circle and the radius... but I don't know what to do next?

 

[engstrom0304]

Calculate the distance Z from the circle centre to point (6,4) using coordinates.

The radius meets the tangent at a right angle. You know the circle radius R.

Therefore for a right angled triangle the length L you want is sqr root of (Z^2 - R^2).

Hope this makes sense.

andy.

Oh ok... thanks that makes sense... So it is just using pythagoras then

Thanks andy.