FIND MISSING MEASURES WHEN GIVEN SURFACE AREA

Problem 1 :

Solution :

Radius r = 3 cm

Surface area = 84π cm²

Surface area of cylinder = 2πrh

84π = (2) (3) π h

84 = 6h

h = 84/6

h = 14 cm

Height of cylinder is 14 cm.

Problem 2 :

Solution :

Radius r = 10 cm

Surface area = 900π cm²

Surface area of cylinder = 2πrh

900π = (2) (10) π h

900 = 20h

h = 900/20

h = 45 cm

Height of cylinder is 45 cm.

Problem 3 :

Solution :

Radius r = 8 cm

Surface area = 56π cm²

Surface area of cylinder = 2πrh

56π = (2) (8) π h

56 = 16h

h = 56/16

h = 3.5 cm

Height of cylinder is 3.5 cm.

Work out the radius of each cylinder below

Problem 4 :

Solution :

Height h = 8 cm

Surface area = 18π cm²

Surface area of cylinder = 2πrh

18π = (2) (8) π r

18 = 16r

r = 18/16

r = 1.125 cm

Radius of cylinder is 1.125 cm.

Problem 5 :

Solution :

Height h = 7 cm

Surface area = 36π cm²

Surface area of cylinder = 2πrh

36π = (2) (7) π r

36 = 14r

r = 36/14

r = 2.571 cm

Radius of cylinder is 2.571 cm.

Problem 6 :

Solution :

Height h = 6 cm

Surface area = 1040π cm²

Surface area of cylinder = 2πrh

1040π = (2) (6) π r

1040 = 12r

r = 1040/12

r = 86.7 cm

Radius of cylinder is 86.7 cm.