Question

In the given figure show that m angle acd = m angle a + m angle b

Answer 1

angle BAC + angle ABC+ angle ACD=180°........(1)

[Angle Sum Property of triangle]

angle ACB + angle ACD=180° .............(2)

[Linear Pair]

Equating (1) and (2),

angle BAC + angle ABC + angle ACD= angle ACB + angle ACD

=> angle BAC a + angle ABC IS EQUALS TO angle ACB

hence proved