(Two isosceles triangles, the outer angle = the sum of the two inner angles)

∠B=∠ADB=( 180-26)/2=77

∠B =∠ADB =( 180-26)/2 = 77 = 2∠C

∠C=77/2=38.5

Page 56, page 1

(1) (180-110)/2 = 35. The base angle is 35 degrees and 35 degrees.

(2)( 180-80)/2=50 base angles 50 and 50

(2)( 180-80*2)=20 vertex angles 20 and 80.

Page 56, question 2

//BC

∠CAD=∠ADB=∠ABD (equilateral and equilateral)