Page 215 - NUMINO_WB_6B
P. 215
124_G6U25_WB_˙—» ¿º 2011.6.23 3:32 PM ˘ ` 17

124-P2-1

Isosceles Triangles and Angles

Triangle ABC is an isosceles triangle and BC DE. Find the unknown

angle. A

40

D E
a C

B

Step 1. What is the sum of the interior angles of a triangle?

Step 2. In an isosceles triangle, the two interior angles are congruent.
Find m ABC and m ACB.

Step 3. Find m ADE.

Step 4. Find m a.
   210   211   212   213   214   215   216   217   218   219   220