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Ch. 7 - Applications of Trigonometry and Vectors
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161Not the one you use?Change textbook
Chapter 8, Problem 3c

In each figure, a line segment of length L is to be drawn from the given point to the positive x-axis in order to form a triangle. For what value(s) of L can we draw the following?
c. no triangle
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Verified step by step guidance
1
Identify the given point's coordinates and the angle it makes with the positive x-axis, if provided, or determine the vertical distance from the point to the x-axis.
Recall that the line segment of length \(L\) is drawn from the point to the positive x-axis, forming a triangle with the x-axis and the segment from the origin to the foot of the perpendicular.
Understand that a triangle can be formed only if the length \(L\) is greater than the shortest distance from the point to the x-axis; if \(L\) is less than this distance, no triangle can be formed.
Express the shortest distance from the point to the x-axis mathematically, which is the absolute value of the y-coordinate of the point, say \(d = |y|\).
Conclude that for no triangle to be formed, the length \(L\) must satisfy \(L < d\), meaning the segment is too short to reach the x-axis and form a triangle.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Triangle Inequality Theorem

The Triangle Inequality Theorem states that the sum of the lengths of any two sides of a triangle must be greater than the length of the remaining side. This principle helps determine whether a triangle can be formed given certain side lengths, ensuring the segments can connect to form a closed shape.
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Distance from a Point to the x-axis

The distance from a point to the x-axis is the absolute value of the point's y-coordinate. This distance is crucial when drawing a segment from the point to the x-axis, as it sets a minimum length for the segment and influences the possible lengths L that can form a triangle.
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Conditions for No Triangle Formation

No triangle is formed when the segment length L violates the triangle inequality, such as being too short or too long relative to other sides. Understanding these conditions helps identify values of L for which a triangle cannot exist, often involving equality or impossible side length combinations.
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