Calculate the surface area of a cylindrical drum of radius 21cm, height 50cm open at the top.

The surface area of a cylindrical drum of radius 21cm, height 50cm open at the top.

radius R = 21cm

height H = 50cm

bottom surface S = 3.14 x R x R = 3.14 x 21 x 21 = 1385 square cm

bottom circumference BS = 3.14 x 2 x R = 3.14 x 2 x 21 = 132 cm

wall surface area WS = BS x H = 132 x 50 = 6600 square cm

whole outside surface area S + WS = 1385 + 6600 = 7985 square cm

whole inside and outside surface area 2(S + WS) = 2(1385 + 6600) = 15970 square cm

step-by-step explanation:

given perimeter: 28cm

length: 9cm

atp,

2(l+w)=p of the reactangle

2(9+x)=28

18+2x=28

2x=28-18

x=10/2

x=5

therefore width is 5 cm

y = 5x + 17

step-by-step explanation:

a perpendicular line will be the opposite reciprocal slope of the given equation.   the slope given is -1/5 so the opposite reciprocal is 5

find b:

7 = 5 (-2) + b

7 = -10 + b

17 = b

write equation

y = 5x + 17