3 Tutor System
Starting just at 265/hour

# Find the surface area of a sphere of radius:i) 10.5 cmii) 5.6 cmiii) 14 cm

i) Radius (r) of sphere = 10.5 cm
Surface area of sphere
= $$4 {\pi} {r}^2$$
= [$$4 × \frac{22}{7} × (10.5)^2$$ $${cm}^2$$]
= [$$4 × \frac{22}{7} × 10.5 × 10.5$$ $${cm}^2$$]
= (88 × 1.5 × 10.5) $${cm}^2$$
= 1386 $${cm}^2$$

Therefore, the surface area of a sphere having radius 10.5cm is 1386 $${cm}^2$$.

ii) Radius (r) of sphere = 5.6 cm
Surface area of sphere
= $$4 {\pi} {r}^2$$
= [$$4 × \frac{22}{7} × (5.6)^2$$ $${cm}^2$$]
= [$$4 × \frac{22}{7} × 5.6 × 5.6$$ $${cm}^2$$]
= (88 × 0.8 × 5.6) $${cm}^2$$
= 394.24 $${cm}^2$$

Therefore, the surface area of a sphere having radius 5.6 cm is 394.24 $${cm}^2$$.

iii) Radius (r) of sphere = 14 cm
Surface area of sphere
= $$4 {\pi} {r}^2$$
= [$$4 × \frac{22}{7} × (14)^2$$ $${cm}^2$$]
= [$$4 × \frac{22}{7} × 14 × 14$$ $${cm}^2$$]
= (4 × 44 × 14) $${cm}^2$$
= 2464 $${cm}^2$$

Therefore, the surface area of a sphere having radius 14 cm is 2464 $${cm}^2$$.