How do you do this Question ?

BmxNoob

Quick question , Cant remember how to do this pass maths Q :

The circle c has equation x² + y² =17.
l is the line x – 4y – 17 = 0.
The line l is a tangent to c at the point T.
(i) Find the co-ordinates of T.


Any help ?
Thanks

LilMissCiara

BmxNoob wrote: »

Quick question , Cant remember how to do this pass maths Q :

The circle c has equation x² + y² =17.
l is the line x – 4y – 17 = 0.
The line l is a tangent to c at the point T.
(i) Find the co-ordinates of T.


Any help ?
Thanks

Do simultaneous equation with the 2!

partyatmygaff

Two methods.

Find the slope of the tangent. Implicitly differentiate the circle function and then let dy/dx = slope of tangent.

Or

Simultaneous equations.

Ficheall

How does the simultaneous equations method work?

PJelly

Ficheall wrote: »

How does the simultaneous equations method work?

The line x – 4y – 17 = 0. So X= 17 + 4y.
Sub that in for X in the circle and solve for Y. Then use that value to solve for X in your line.
Voila. Marks

Shanee.

Ficheall wrote: »

How does the simultaneous equations method work?

Its more substitution that simultaneous equations.