Question

find the unknown angle.
Don't answer if you don't know. Don't be greedy of points.
No spam​

Answer 1

$\rm{In\: First\: Figure\: ;\: \angle a+\angle a=120^\circ\quad...\:Exterior \: Angle\: Property}$

$\longrightarrow\rm{2\angle a = 120^\circ }\longrightarrow\rm{\angle a = 120^\circ/2=60^\circ }$

$\rm{In\:Second\: Figure\: ;\: Consider\:\angle x \: as \: unknown \:angle}$

$\longrightarrow\rm{\angle x + 140^\circ=180^\circ\quad...\:Angle\:Sum\:Property}$

$\longrightarrow\rm{\angle x =180^\circ-140^\circ=40^\circ}$

$\rm{In\: Third\: Figure\: ;\: \angle a + 105^\circ=180^\circ\quad and\quad\angle b + \angle b =105^\circ}$

$\longrightarrow\rm{\angle a = 180^\circ-105^\circ=75^\circ\quad and\quad 2\angle b = 105^\circ\longrightarrow \angle b = 105^\circ/2=52.5^\circ}$