31. CHỌN (D).SXQ=2 Π R H = 2 Π .6.8=96 Π CM2.STP = SXQ + 2SĐÁY = 96...

4.31. Chọn (D).

S

xq

=2

π

r h = 2

π

.6.8=96

π

cm

2

.

S

tp

= S

xq

+ 2S

Đáy

= 96

π

+ 2(

π

.6

2

) = 96

π

+ 72

π

= 168

π

cm

2

.

V=

π

r

2

h =

π

.6

2

.8 = 288

π

cm

3