Question

In the given figure, AB= AC and angle ACD = 100 degree find A angle

Answer 1

Answer:

Angle A = 20°

Using supplementary angles

isoscles triangle theorem

angle sum property

Answer 2

Answer:

Angle ACB = 180-100

=80

AB=AC (given )

Angle ABC = Angle ACB = 80 degree

Angle ACD = Angle BAC + Angle ABC (exterior angle theorem )

100 degree =Angle BAC + 80 degree

Angle BAC = 100 - 80

= 20 degree