4. The circumference of the base of a cylinder is 88 cm and its height is 15 cm. Find
curved surface area and total surface area.
5. A rectangular strip 25 cm x 7 cm is rotated about the longer side. Find the total surface area of solid thus generated
Answers
Answer:
The circumference of the base of a cylinder is 88 cm and its height is 15 cm. Find its curved surface area and total surface area.
Step-by-step explanation:
We have,
Circumference of base of cylinder = 88 cm
Height of cylinder = 15 cm
By using the formula,
Circumference of base of cylinder = 2πr
So,
2πr = 88
2 × 22/7 × r = 88
r = 88×7 / 44
= 616/44
= 14cm
Radius of cylinder = 14 cm
∴ Curved surface area of cylinder = 2πrh
= 2 × 22/7 × 14 × 15
= 1320 cm2
∴ Total surface area area of cylinder = 2πr (h+r)
= 2 × 22/7 × 14 (15 + 14)
= 2 × 22/7 × 14 × 29
= 2552 cm2
Answer:
1) 5280 cm²
2) 1408 cm² y
Step-by-step explanation:
1) Let the radius of the base of the cylinder be r cm.
2πr=88
r=
2×22
88×7
r=14
h=60cm
Volume =πr
2
h=
7
22
×(14)
2
×60
=36960
C.S.A=2πrh
=2×
7
22
×14×60
=5280 cm ²
2) Dimension of rectangular strip = 25 cm × 7 cm When this strip is rotated about its longer side, Height of cylinder becomes = 25 cm Radius = 7 cm ∴ Total surface area of cylinder = 2πr (h+r) = 2 × 22/7 × 7 (25 + 7) = 2 × 22/7 × 7 × 32
= 1408 cm2