Question

Please help with by finding the surface area of numbers 122 to 124 which are the top one ands please read 125 a and 126 to find the answer. Please answer all questions with a good explanation if not u will be reported. Thanks

Answer 1

Surface area of cylinder is 2 (pi)rh+2(pi)r^2
this is the area of the side [(2 (pi)rh] and the two circles together [2 (pi)r^2]

122. r=24
h=15
2 (3.14)24×15+2 (3.14)24^2
6.28×24×15+6.28×24^2
2260.8+3617.28
5878.08mm

123. r=5
h=8
2 (3.14)5×8+2 (3.14)5^2
6.28×5×8+6.28×5^2
251.2+157
408.2cm

124. the surface area of a cylinder that has a hole is going to be
surface area of big cylinder-2small area circles (the holes) + the area of the holes sides

hopefully that isn't too confusing

big radius: 8
height: 14

little radius: 2.5
height: 14

2 (3.14)8×14+2 (3.14)8^2
6.28×8×14+6.28×8^2
703.36+401.92

1105.28in (area of big cylinder)

2 (3.14)2.5^2 (two small holes)
6.28×2.5^2
39.25in (area of holes)

2 (3.14)×2.5×14 (area of side)
6.28×2.5×14
219.8in

1105.28-39.25+219.8
1066.03+219.8

1285.83in total surface area

125. h=20
r=6 since diameter is a foot or 12 in, half of that is 6
2 (3.14)6×20+2 (3.14)6^2
6.28×6×20+6.28×6^2
753.6+226.08
979.68in

126. first radius= 10
first height = 6

second radius= 6
second height= 10

2 (3.14)10×6+2 (3.14)10^2
6.28×10×6+6.28×10^2
376.8+628
1004.8in (surface area of first cylinder)

2 (3.14)6×10+2 (3.14)6^2
6.28×6×10+6.28×6^2
376.8+226.08
602.88in (surface area of second cylinder)

1004.8-602.88= 401.92

the surface area of the cylinder with radius 10 and height 6 is GREATER that the surface area of the cylinder with radius 6 and height 10..
by 401.92in