What is the total surface area of a cone having radius r/2 and height 21?
Answers
Step-by-step explanation:
The total surface area of cone is \frac{22}{7} \times \frac{r}{2} \times \sqrt{21^2+(\frac{r}{2})^2}+\frac{22}{7} (\frac{r}{2})^2
7
22
×
2
r
×
21
2
+(
2
r
)
2
+
7
22
(
2
r
)
2
Step-by-step explanation:
Radius of cone = \frac{r}{2}
2
r
Height of cone = 21 cm
Total surface area of cone = \pi r \sqrt{h^2+r^2}+\pi r^2πr
h
2
+r
2
+πr
2
Total surface area of cone =\frac{22}{7} \times \frac{r}{2} \times \sqrt{21^2+(\frac{r}{2})^2}+\frac{22}{7} (\frac{r}{2})^2
7
22
×
2
r
×
21
2
+(
2
r
)
2
+
7
22
(
2
r
)
2
Hence The total surface area of cone is \frac{22}{7} \times \frac{r}{2} \times \sqrt{21^2+(\frac{r}{2})^2}+\frac{22}{7} (\frac{r}{2})^2
7
22
×
2
r
×
21
2
+(
2
r
)
2
+
7
22
(
2
r
)
2
Step-by-step explanation:
Given,
Radius (r) = r / 2
Height (l) = 21 units ( You haven't mentioned the units in the question)
Now,
T.S.A = πr(l + r)
= (πr/2) × ( 21 + r/2)
= (πr)/2 × (42+r)/2
= (42πr + πr²)/4
Hope it helps