A circle has radius \(4.5\,\text{cm}\). Lines \(g_1\), \(g_2\), and \(g_3\) have the following perpendicular distances from the center:
\(d_1 = 35\,\text{mm}\)
\(d_2 = 45\,\text{mm}\)
\(d_3 = 5\,\text{cm}\)
Classify each line as a secant, a tangent, or an exterior line with no intersection. Justify each classification by comparing its distance with the radius.
Hints
- Convert all lengths to the same unit.
- Compare each perpendicular distance with the radius.
- Relate the comparison to zero, one, or two intersection points.
Solution
1. Convert all measurements to centimeters: \(r = 4.5\,\text{cm}\), \(d_1 = 3.5\,\text{cm}\), \(d_2 = 4.5\,\text{cm}\), and \(d_3 = 5\,\text{cm}\).
2. Since \(d_1 < r\), line \(g_1\) intersects the circle twice and is a secant.
3. Since \(d_2 = r\), line \(g_2\) intersects the circle once and is a tangent.
4. Since \(d_3 > r\), line \(g_3\) does not intersect the circle and is exterior to the circle.
Answer
\(g_1\): secant because \(d_1 < r\). \(g_2\): tangent because \(d_2 = r\). \(g_3\): exterior line because \(d_3 > r\).