In ΔABC, side BC is produced to D. If ∠ABC = 40° and ∠ACD = 120°, then ∠A = ?
ACD + 
ACB = 180 (Linear pair of angles)
ACB = 60o
ABC = 40o
As we know that
ACB + 
ACB + 
BAC = 180o
BAC = 180 – 60 – 40
=80o
30
In ΔABC, side BC is produced to D. If ∠ABC = 40° and ∠ACD = 120°, then ∠A = ?
ACD + ACB = 180 (Linear pair of angles)
ACB = 60o
ABC = 40o
As we know that
ACB + ACB + BAC = 180o
BAC = 180 – 60 – 40
=80o