Question

ce set 7.1
1. Find the volume of a cone if the radius of its base is 1.5 cm and its perpendicular
height is 5 cm.
​

Answer 1

Given :-

• Radius of cone (r) = 1.5 cm
• Perpendicular height of cone (h) = 5 cm

To Find :-

• The volume of a cone.

Solution :-

As we know that,

⭐ Volume of cone = ¹/3 × πr²h

[ Putting values ]

↪ Volume of cone = ¹/3 × 22/7 × (1.5)² × 5

↪ Volume of cone = ¹/3 × 22/7 × (3/2)² × 5

↪ Volume of cone = ¹/3 × 22/7 × 9/4 × 5

↪ Volume of cone = 22/7 × 3/4 × 5

↪ Volume of cone = 11/7 × 3/2 × 5

↪ Volume of cone = 165/14

↪ Volume of cone = 11.78 cm³ ⭐

Hence,

• The volume of cone is 11.78 cm³.

For information:

• l² = r² + h²
• Curved surface area of cone = πrl
• Total surface area of cone = πr(l + r)

Answer 2

ɢɪᴠᴇɴ :-

• Radius of the cone is 1.5 cm
• Perpendicular height of cone is 5 cm

ᴛᴏ ꜰɪɴᴅ :-

• The volume of a cone.

ꜱᴏʟᴜᴛɪᴏɴ:-

$\begin{lgathered}\tt\green{As \: we \: know \: that, \;}\\ : \implies \tt{Volume\: of \: cone} = \frac{1}{3}\pi r^{2}h\\ \\ : \implies \tt{Volume \: of \: cone} = \frac{1}{3} \times \frac{22}{7}\times 1.5^{2} \times5\\ \\ : \implies \tt{Volume\: of \: cone} = 3.14\times 3.75\\ \\ { : \implies \tt{Voulme\: of \: cone} =11.775\: {cm}}^{3}\end{lgathered}$

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$\large{\pink{\underline{\tt{Maths\;Alert!♡}}}}$

✻The lateral surface area of a cone is given by

   LSA of a cone = π r l

✻The total surface area of a cone is given by

   TSA of a cone = π r (r + l)

✻ Volume of a cone is given by

  Volume of cone = 1/3 × π × r² ×