Question

In triangle abc side BC is produced to d if angle abc equal to 40 and angle ACD equal to 120 then find angle a

Answer 1

bd is a straight line

angle(acd+acb)=180

angle (120+acb)=180

angle (acb)=180-120

angle(acb)=60

according to triangle theorem

sum of all angles=180

angle(abc+bca+cab)=180

angle (40+60+cab)=180

angle (cab)=180-100

angle (cab)=80