h = 30 cm
\alpha = 80/2 = 40^\circ
\frac{h}{c}=cos \alpha
\frac{h}{c}=cos 40\circ
\frac{30}{c}=0,766
c=\frac{30}{0,766}
c\approx39,16[cm] ramię trójkąta
z twierdzenia Pitagorasa
(\frac{a}{2})^2=39,16^2-30^2
\frac{a^2}{4}=1533-900
\frac{a^2}{4}=633
a^2=4*633
a=\sqrt{2532}
a\approx50,3
Ob=a+2c=25,2+2*39,16\approx103,5[cm]
P=\frac{1}{2}ah=\frac{1}{2}*50,3*30=\frac{1509 }{2} =754,5[cm^2] (około)