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.) |
|||
Line 1: | Line 1: | ||
− | The ''' | + | The '''Base Angle Theorem''' states that in an [[isosceles triangle]], the measures of the angles opposite the equal-measuring sides are equal. |
==Proof== | ==Proof== |
Revision as of 21:42, 20 September 2008
The Base Angle 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
.