Question

in triangle ABC it is given out AB/AC=BD/DC if angle B=70degree and angle C=50degree then angle BAD=?

Answer 1

angleB =70 angleC =50
A+ B+C =180( angle sum property)
Let angle A be x
x+70+50=180
x+120=180
x=180-120
x=60°

Answer 2

We know that the Sum of the angle of all sides of a triangle is $180^\circ$.

Given: $\frac{AB}{AC}=\frac{BD}{DC}$

$\angle A+\angle B+\angle C=180^\circ\\\angle A+70^\circ+50^\circ=180^\circ$

        $\angle A+120^\circ=180^\circ$

                    $\angle A=180^\circ-120^\circ\\\angle A=60^\circ$

$\angle BAD=\angle DAC=\frac{1}{2}\angle BAC$

$\angle BAD=\frac{1}{2}\times \angle BAC$

$\angle BAD=\frac{1}{2}\times 60^\circ$

$\angle BAD=30^\circ$