Elementary Geometry For College Students, 7e
7th Edition
ISBN:9781337614085
Author:Alexander, Daniel C.; Koeberlein, Geralyn M.
Publisher:Alexander, Daniel C.; Koeberlein, Geralyn M.
ChapterP: Preliminary Concepts
SectionP.CT: Test
Problem 1CT
Related questions
Question
Number 3

Transcribed Image Text:11:04 PM Wed Sep 21
=
Section 4 The Circle
Our second theorem concerns two tangents to a circle drawn from an external
point, Fig. 6-68.
Two Tangents
Drawn to a Circle
Here, PA equals PB. Also, angle APC equals
angle BPC.
Turning now from tangents to chords, Fig. 6-69, we have the theorem
If two chords in a circle intersect, the product of
the parts of one chord equals the product of the parts
of the other chord
Here,
Intersecting
Chords
Two tangents drawn to a circle from a point
outside the circle make equal angles with a line
drawn from the circle's center to the external
point. The distances from the external point
to each point of tangency are equal.
+++ Example 22: Find x in Fig. 6-70.
Solution: By theorem 85 we can write
刀
ab = cd
16.3x10.1(12.5)
x =
:
10.1(12.5)
16.3
= 7.75
84
85
Semicircle
Any angle inscribed in a semicircle is a right angle.
+++ Example 23: Find the distance x in Fig. 6-71.
Solution: By statement 82, we know that = 90°. Then, by the Pythagorean theorem,
x=√(250)² (148)² = 201
82
***
Exercise 4 The Circle
1. Find the circumference and area of a circle of radius 4.82 cm.
2. Find the circumference and area of a circle of radius 2.385 in.
3. Find the radius and area for a circle whose circumference is 74.8 in.
4. Find the radius and area for a circle whose circumference is 2.73 m.
5. Find the radius and circumference of a circle whose area is 39.5 ft².
6. Find the radius and circumference of a circle whose area is 2.74 m².
7. Inscribed and Circumscribed. A polygon is said to be inscribed in a circle if
every vertex of the polygon lies on the circle. The circle is then said to be cir-
cumscribed about the polygon. A polygon is said to be circumscribed about a
circle if the circle is tangent to each side of the polygon. The circle is then said
to be inscribed in the polygon.
8+1
QAA Ę
FIGURE 6-68
a
FIGURE 6-69
16.3
12.5
FIGURE 6-70
0
FIGURE 6-71
A
193/1040
B
10.1
193
b
Semicircle of radius = 125
x
91%
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