t is of interest to find the equations of the tangent to x^2+y^2=10 at (a,b) where the point is on the curve.
Taking the derivative, 2+2′=0⇒′=− , and so the slope of the tangents are =− .
The equation of the tangent looks like
=−+⇒=−2+⇒=2+2=10
The equation becomes, +=10 .
Now use this formula.
