Question

Prove that angle sum property is 180

Answer 1

it forms a straight angle

Answer 2

Answer:

$\red{ \bold{to \: prove}} \\ \angle1 + \angle2 + \angle3 = 180 \degree$

Construction:

Draw DE || BC through A

$\angle4 = \angle2 \\ \angle5 = \angle3$

(angle 4,2 and angle 5,3 are alternate interior angles)

$\implies \: \angle1 + \angle2 + \angle3 = \angle4 + \angle5 + \angle6$

$\angle4 + \angle5 + \angle6 = 180 \degree$

(Because angles 4,5 and 6 are on a straight line)

$\tt{\bold{ \red{hence \: proved}}}$