Question

find CSA and TSA of a cone whose height is 28 cm and diameter is 42 cm​

Answer 1

Given :

⬤ Height of Cone = 28 cm

⬤ Diameter of Cone = 42 cm

To Find :

⬤ Curved Surface Area of Cone .

⬤ Total Surface Area of Cone .

Formula Used :

$\sf[\:{Curved\:Surface\:Area\:of\:Cone=\pi{r}l}\:]$

Solution :

• Diameter = 42 cm
• Radius = 42/2 = 21 cm

First , We have to Calculate the Slant Height (l) of the Cone . Hence :

l² = h² + r²

l² = (28)² + (21)²

l² = 784 + 441

l² = √1225

l = 35

Therefore , Slant Height of the Cone is 35 cm .

Now :

According to the Formula :

πrl

22/7 × 21 × 35

22 × 21 × 5

2310

Therefore , The Curved Surface Area of the Cone is 2310 cm² .

Formula Used :

$\sf[\:{Total\:Surface\:Area\:of\:Cylinder=\pi{r}(l+r)}\:]$

Solution :

According to the Formula :

πr (l + r)

22/7 × 21 (35 + 21)

22 × 3 (35 + 21)

66 × 56

3696

Therefore , The Total Surface Area of the Cone is 3696 cm² .