d.) The minute hand on a watch is 1.2cm long. What distance does the dip of this hand travel in an hour( to one decimal place, include units)?
e.) A circular table is 2.3m across. What is the area of the table top (to one decimal place, include units.)
źródło:
d) r = 1,2 cm
l=2\pi r obwód okręgu
1 h = 60 min
60*l=60*2\pi r=120\pi r=120*3,14*1,2=452,16\approx452,2[cm] <–odpowiedź
e) d = 2,3 m r=\frac{1}{2}d=\frac{1}{2}*2,3=1,15[m]
P=\pi r^2
P=\pi * (1,15)^2=3,14*1,3225\approx 4,2[m^2] <–odpowiedź