2. Isosceles Triangles

3. Base Angles
If 2 angles in a triangle are congruent, then the sides opposite them are congruent.

4. Solve for x.
2x + 25 = 7
2x = -18 12
x = -9

5. Base Angles
If 2 sides in a triangle are congruent, then the angles opposite them are congruent.

6. Solve for x.
6x + 1 = 55
6x = 54 3
x = 9

7. The measure of the exterior angle is equal to the sum of two nonadjacent interior angles
(Remote Interior Angles: <1 and <2) 1
m1+m2 =m3 2 3
Essential Question: How do the external angles of a triangle relate to the two remote interior angles?

8. Find the value of x.
430 x
380
Essential Question: How do the external angles of a triangle relate to the two remote interior angles?

9. Find the value of x.
720
1480 x0
Essential Question: How do the external angles of a triangle relate to the two remote interior angles?

10. Find the value of x.
Essential Question: How do the external angles of a triangle relate to the two remote interior angles?