Pearson Geometry Common Core, 2011
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Pearson Geometry Common Core, 2011 View details
1. Tangent Lines
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Exercise 4 Page 766

To understand how the given phrases are used differently, you should consider the trigonometric ratios.

See solution.

Practice makes perfect

To understand how the phrases tangent ratio and tangent of a circle are used differently, we can begin by recalling the definitions of them.

  • Tangent Ratio: The tangent ratio is the ratio of the length of the leg opposite an angle to the length of the leg adjacent the same angle in a right triangle.
  • Tangent of a Circle: The tangent of a circle is a line in the plane of the circle that intersects the circle in exactly one point.
To compare the phrases, let's try to visualize both of them.

Tangent Ratio

Let △ ABC be a right triangle with angles α and β.

Considering the definition, we can write two different tangent ratios as tangent equals "opposite over adjacent." tan α=AB/BC and tan β=BC/AB

Tangent of a Circle

Let's consider a circle centered at point O and a line that intersects the circle only in point P.

We can conclude that, by the definition, line l is the tangent line of the circle.

Comparison

When we contrast the phrases, we can see that they are completely different. The tangent ratio is a numerical value in a right triangle while the tangent of a circle is a geometric figure.