Ratio of Segments on Chord Perpendicular to Diameter

MathematicsGeometry - Circles and TrianglesMediumSTEM

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In the figure shown, points $U, V, X,$ and $Z$ lie on the circle, and $VX < VZ$. Segment $XZ$ is the diameter of the circle and has length $150$. Segment $XZ$ is perpendicular to segment $UV$ at point $Y$, and $VY = \sqrt{296}$. If $\frac{XY}{YZ} = k$, what is the value of $k$?

This question includes visual content: A circle with points U, V, X, and Z on its circumference. Segment XZ is a chord shown as the diameter. Segment UV is another chord. The two chords intersect at point Y. There is a right-angle symbol at point Y, indicating XZ is perpendicular to UV. There is also a right-angle symbol at point V in triangle ZVX, indicating angle ZVX is 90 degrees (angle inscribed in a semicircle). Point Y lies on segment XZ such that it divides the diameter into XY and YZ. Point Y also lies on segment UV.

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Step by Step Written Solution

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Step 1

Let's solve this geometry problem involving a circle, its diameter, and a perpendicular chord. We are given several geometric properties and lengths, and we need to find the ratio k.

Given Information

- $XZ$ is the diameter, length $= 150$

- $XZ \perp UV$ at point $Y$

- $VY = \sqrt{296}$

- $VX < VZ$

- Goal: Find $k = \frac{XY}{YZ}$

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Step 2

First, we observe triangle Z V X. Since X Z is a diameter and V lies on the circle, the inscribed angle Z V X is a right angle by Thales's Theorem.

Step 1: Geometry Properties

$$\angle ZVX = 90^\circ \text{ (Inscribed angle in a semicircle)}$$
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Step 3

We are also given that the diameter X Z is perpendicular to the chord U V at point Y. This means triangle Z V X is partitioned into two smaller right triangles, Z Y V and V Y X, which share altitude V Y.

$$VY \perp XZ \implies \triangle ZYV \sim \triangle VYX \sim \triangle ZVX$$
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Step 4

Let's use the Geometric Mean Theorem for altitude V Y in the right triangle Z V X. This theorem state that the square of the altitude equals the product of the two segments of the hypotenuse.

Step 2: Applying Geometric Mean Theorem

$$VY^2 = XY \cdot YZ$$
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Step 5

We know that V Y is the square root of two hundred ninety-six. Squaring this value gives us two hundred ninety-six.

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Step 6

We also know that the diameter X Z is one hundred fifty. The sum of the segments X Y and Y Z must equal the total length of the diameter.

$$XY + YZ = 150$$
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Step 7

Now we have a system of two equations with two variables. Let's solve for X Y and Y Z. From the second equation, we can express Y Z as one hundred fifty minus X Y.

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Step 8

Substitute this expression for Y Z back into our product equation.

Step 3: Solving the System

$$XY(150 - XY) = 296$$
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Step 9

Expanding the terms, we get one hundred fifty X Y minus X Y squared equals two hundred ninety-six.

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About This Question

Subject
Mathematics
Topic
Geometry - Circles and Triangles
Difficulty
Medium
Exam
STEM
Question Type
Open Ended

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