Geometryhard · Past Paper
If the line y = mx + c is tangent to the circle x^2 + y^2 = r^2, then:
Ac^2 = r^2(1 + m^2)
Bc^2 = r^2(1 - m^2)
Cc = r*m
Dc = r/m
✓ Correct Answer: A — c^2 = r^2(1 + m^2)
This is the condition of tangency for a line and a circle centered at the origin.
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