Question

in a triangle abc from angle a a line is drawn on bc at o and ab =oc and angle b=80 and angle c=20 find angle aob

Answer 1

IN TRIANGLE ABC

angle A +angle B +angle C =180

We have angle A =60

Therefore angle C +angle B =180-60= 120

Now we have bisectors of angle C and angle B

Therefore if angle B and angle C measures 180

Their bisector would measure half of them

Because angle bisector =total angle /2

Therefore angle OBC and angle OCB would measure

120/2=60

Now in triangle angle BOC, angle OBC, angle OCB would measure 180

Angle BOC =180 - (angle OBC and angle OCB)

(angle OBC and angle OCB)=60

Angle BOC =180-60

= 120