Answer:
Step-by-step explanation:
By triangle sum theorem,
73°+ 39° + m∠1 = 180°
m∠1 = 180° - 102°
m∠1 = 78°
Since, m∠1 = m∠2 [Vertically opposite angles]
m∠2 = 78°
Sum of interior angles of a polygon = (n - 2)×180°
Where n = number of sides of the polygon
Sum of the interior angles of a quadrilateral = (4 - 2)×180°
= 360°
Therefore, 77° + m∠3 + 90° + m∠2 = 360°
77° + m∠3 + 90° + 78° = 360°
m∠3 = 360° - 245°
m∠3 = 115°
