Question Number 180298 by mnjuly1970 last updated on 10/Nov/22
Answered by mr W last updated on 10/Nov/22
Commented by mr W last updated on 10/Nov/22
$$\mathrm{2}\beta+\mathrm{2}\gamma+\mathrm{120}°=\mathrm{180}° \\ $$$$\Rightarrow\beta+\gamma=\mathrm{30}° \\ $$$$\alpha+\mathrm{60}°+\left(\mathrm{90}°−\beta\right)+\left(\mathrm{90}°−\gamma\right)=\mathrm{360}° \\ $$$$\alpha−\beta−\gamma=\mathrm{120}° \\ $$$$\Rightarrow\alpha=\mathrm{120}°+\mathrm{30}°=\mathrm{150}°\:\checkmark \\ $$
Commented by mnjuly1970 last updated on 10/Nov/22
$$\:\:{thanks}\:{alot}\:\:{sir}\:{W} \\ $$