Question

The total surface are of cone is 704sq.cm and the ratio of the
base is 7 cm
Find the slant height of the cone?​

Answer 1

✮ Question

• The total surface area of cone is 704 sq.cm and the radius of the  base is 7 cm . Find the slant height of the cone?​

✮ Given

• Total surface are of cone is 704 sq.cm
• Radius of the base is 7 cm

✮ To Find

• Slant height of the cone

✮ Answer  

• Slant Height is 25 cm

✮ Explanation

♣ Total surface area of cone = πr² + πrl

Where :

• r = radius
• l = slant height

Total surface area of cone = πr² + πrl

Taking πr common

⇒ 704 = πr(r + 1)

⇒ 704 = π × r(l + r)

⇒ 704 = π × 7(l + r)

Since π = 22/7

⇒ 704 = 22/7 × 7(l + r)

⇒ 704 = 22/1 × 1(l + r)

Since Radius = 7

⇒ 704 = 22(l + 7)

⇒ 704 = 22l + 22 × 7

⇒ 704 = 22l + 154

⇒ 704 - 154  = 22l + 154 - 154

⇒ 550  = 22l

⇒ 550/22  = l

⇒ 25  = l

∴ Slant Height is 25 cm