a^2+b^2=c^2
P=(a*h)/2
Obw=a+b+c
a)
21^2+20^2=441+400=441
441=c^2 => c=29
Obw=20+21+29=70
P=20*21/2=210
b)
7^2+24^2=49+576=625 => c=25
Obw=7+24+25=56
P=7*24/2=84
c)
sqrt(5) - > pierwiastek z 5
2^2+4^2=4+16=20=4*5 => c=2*sqrt(5)
Obw=2+4+2sqrt(5)=6+2sqrt(5)
P=2*4/2=4
