precalculus
posted by yuia .
tangents are drawn from the point (4,0) to the circle x^2 +y^2 =1. find the slopes of the tangent.

If the tangent hits the circle at (h,k)
it has length
L^2 + 1 = 16
L = sqrt(15)
h^2 + k^2 = 1
(4+h)^2 + k^2 = 15
Solve for h,k, and the slope is
k/(4+h)
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