Question

Q11. Find the surface area of a sphere of radius 7 cm? *



616 cubic cm

161 cubic cm

212 cubic cm


​

Answer 1

Given:-

• Radius of a sphere is 7 cm.

⠀

To find:-

• Surface area of a sphere.

⠀

Solution:-

★Formula used:-

Surface area of sphere = 4πr²

⠀

→ 4 × 22/7 × 7 × 7

→ 4 × 22 × 1 × 7

→ 88 × 7

→ 616 cm³

⠀

Hence,

• the surface area of a sphere is 616 cm³.

⠀

Therefore,

• Option 1 is correct.

⠀

More Formulas:-

→ Area of rectangle = length × breadth sq.units

→ Perimeter of square = 4 × side units

→ Area of square = side × side sq.units

→ Perimeter of circle = 2πr units

→ Area of circle = πr² sq.units

→ Perimeter of parallelogram = 2 × (a + b) units

→ Area of parallelogram = base × height sq.units

→ Perimeter of rhombus = 4 × side units

→ Area of rhombus = 1/2 × diagonal (1) × diagonal (2) sq.units

→ Perimeter of equilateral triangle = 3 × side units

→ Area of equilateral triangle = √3/4 × a² = 1/2 × side × height sq.units

→ Perimeter of trapezoid = (Sum of all sides) units

→ Area of trapezoid = 1/2 × height × (sum of parallel sides) sq.units

Answer 2

☾✪Given:-✪☽

• Radius of a sphere ↣ 7 cm

━━━━━━━ ★ ━━━━━━━

☾✪To Find:-✪☽

• Surface area of a sphere.

━━━━━━━ ★ ━━━━━━━

☾✪Formula:-✪☽

• Surface area of a sphere↣4πr²

━━━━━━━ ★ ━━━━━━━

☾✪Solution:-✪☽

$\small \therefore \sf Surface \: area \: of \: a \: sphere \: ⇢4\pi {r}^{2}$

$\small \sf ⇢\: 4 \times \frac{22}{7} \times ( {7)}^{2}$

$\small \sf⇢ \: 4 \times \frac{22}{ \cancel7} \times \cancel7 \times 7$

$\small \sf ⇢88 \times 7$

$\small \sf⇢616 \: cm {}^{2}$

━━━━━━━ ★ ━━━━━━━

• Hence, (a) 616 cm² is correct . ✓

━━━━━━━ ★ ━━━━━━━

☾✪More Information:-✪☽

• $\small \sf \: Surface \: Area \: of \: a \: Sphere \large\leadsto \small \boxed{ \bf 4\pi {r}^{2} }$

• $\small \sf \: Curved \: Surface \: Area \: of \: a \: Hemisphere \large\leadsto \small \boxed{ \bf 2\pi {r}^{2} }$

• $\small \sf \: Total \: Surface \: Area \: of \: a \: Hemisphere\large\leadsto \small \boxed{ \bf 3\pi {r}^{2} }$

• $\small \sf \: Volume \: of \: a \: Cuboid \large\leadsto \small \boxed{ \bf l \times b \times h}$

• $\small \sf \: Volume \: of \: a \: Cube \large\leadsto \small \boxed{ \bf {a}^{3} }$

• $\small \sf \: Volume \: of \: a \: Cylinder \large\leadsto \small \boxed{ \bf \pi {r}^{2}h }$

• $\small \sf \: Volume \: of \: a \:Cone\large\leadsto \small \boxed{ \bf \frac{1}{3}\pi r {}^{2} h }$

• $\small \sf \: Volume \: of \: a \: Sphere \large\leadsto \small \boxed{ \bf \frac{4}{3} \pi r {}^{3} }$

• $\small \sf \: Volume \: of \: a \: Hemisphere \large\leadsto \small \boxed{ \bf \frac{2}{3}\pi {r}^{3} }$

━━━━━━━ ★ ━━━━━━━