Download - 12.1 Tangent Lines
Transcript
Theorem 12-1:
If a line is tangent to a circle, then the line is perpendicular
to the radius drawn to the point of tangency.
Point of tangencyA
BO
PABOP
Example:ML and MN are tangent to O. Find the value of x.
M
L
N
O 1170 x
The sum of the angles of a
quadrilateral is 3600
1170+900+900+x=3600
2970+x=3600
x=630
Example:Is ML tangent to
N at L?
M
L
7
N
24
25
a2+b2=c2 72+242=252
49+576=625 625=625
Yes
Theorem 12-1:
The two segments tangent to a circle from a point outside of the circle are congruent.
M
L
N
O
LMNM
Example: O is inscribed in ABC.
Find the perimeter of ABC?
C
A8
B
10
15
8
10
15
8+8+10+10+15+15 68