in a triangle ABC ANGLE A +ANGLEB =65 ,ANGLEB +C=140 FIND A B C?
First we, excide the line BC to point D.
By exterior angle angle property angle A + angle B= angle ACD=65,
It is given that angle A + angle B=65, Angle B+ angle ACB=140.
then, by linear pair angle ACB+ angle ACD=180,
angle ACB=180-65=115,
now we have angle ACB=115,as it is given that angle ACB+ angle B=140,angle B=140-115=25,
we also knew that angle A+angle B=65,than
angle A+ angle B=65,= angle A+25=65,
so, angle A =65-25=40.
SO, angle A=40,
angle B=25,
angle ACB=115.