Difference between revisions of "Base Angle Theorem"
m (Hinge Theorem moved to Base Angle Theorem: It's not called the Hinge Theorem. It's called the Base Angle Theorem.) |
|
(No difference)
|
Revision as of 21:41, 20 September 2008
The Hinge Theorem states that in an isosceles triangle, the measures of the angles opposite the equal-measuring sides are equal.
Proof
Since the triangle only has three sides, the two equal-measuring sides must be adjacent. Let them meet at vertex .
Now we draw height to
. From the Pythagorean Theorem,
, and thus
is similar to
, and
.