In Fig. 4.58, is a triangle such that , . Find.
We have
AB/AC=BD/DC
∴ ∠1=∠2
IN ⊿ABC
∠A+∠B+∠C=180
∠A+70+50=180
∠A+120=180
∠A=180-120
∠A=60
∠1+∠2=60 (∠1+∠2=∠A)
∠1+∠1=60 (∠1=∠2)
2∠1=60
∠1=60/2
∠1=30
∠BAD=30