P=\sqrt{p(p-a)(p-b)(p-c)} gdzie p=\frac{a+b+c}{2}
zrobię a) i d) a pozostałe analogicznie
a)
p=\frac{3+4+5}{2}=6
P=\sqrt{6(6-3)(6-4)(6-5)}=\sqrt{6*3*2*1}=\sqrt{36}=6cm^2
d)
p=\frac{5+\sqrt{11}+6}{2}=\frac{11+\sqrt{11}}{2}
P=\sqrt{\frac{11+\sqrt{11}}{2}(\frac{11+\sqrt{11}}{2}-5)(\frac{11+\sqrt{11}}{2}-\sqrt{11})(\frac{11+\sqrt{11}}{2}-6)}=\sqrt{(\frac{11+\sqrt{11}}{2})^2(1-5)(1-\sqrt{11})(1-6)}=\frac{11+\sqrt{11}}{2}\sqrt{(-4)(1-\sqrt{11})(-5)}=\frac{11+\sqrt{11}}{2}\sqrt{20(1-\sqrt{11})}=\frac{11+\sqrt{11}}{2}\sqrt{4*5(1-\sqrt{11})}=2\frac{11+\sqrt{11}}{2}\sqrt{5(1-\sqrt{11})}=2\frac{11+\sqrt{11}}{2}\sqrt{5-5\sqrt{11}}=11+\sqrt{11}\sqrt{5-5\sqrt{11}}=cdn...