Lesson Example Discussion Quiz: Class Homework |
Step-5 |
Title: Surface area of 3D shapes(sphere, prism, cylinder) |
Grade: 4-a Lesson: S3-L2 |
Explanation: Hello Students, time to practice and review the steps for the problem. |
Lesson Steps
| Step | Type | Explanation | Answer |
|---|---|---|---|
1 |
Problem |
The height of a cylinder is 12cm and its radius is half that height. Find its surface area 10 cm and 18 cm, respectively, along with the height of the equilateral triangular bases being 19 cm? |
|
2 |
Step |
The given values are |
h = 12 cm |
3 |
Formula |
The surface area of the cylinder is |
A = 2πrh + \$2πr^2\$ |
4 |
Hint |
The radius of the cylinder is half of its height, then the value of radius is |
r = \$h/2\$ r = \$12/2\$ r = 6 |
5 |
Step |
So the radius of a cylinder is |
6 cm |
6 |
Step |
Substitute the values of height and radius in given equation |
\$"A" =(2π times 6 times 12) + 2π times 6^2\$ \$"A" =(2 times 3.14 times 6 times 12) + (2 times 3.14 times 36)\$ A = 452.16 + 226.08 |
7 |
Step |
simplify the equation |
A = 678.24 |
8 |
Step |
Hence the surface area of the cylinder is 678.24 sq.cm |
|
9 |
SumUp |
Can you summarize what you’ve understood in the above steps? |
|
10 |
Choice.A |
This is not correct because it seems to have miscalculated the surface area of the triangular prism |
656.24 sq.cm |
11 |
Choice.B |
This is not correct because it seems to have miscalculated the surface area of the triangular prism |
684.24 sq.cm |
12 |
Choice.C |
This is correct because it correctly calculates the surface area of the triangular prism |
678.24 sq.cm |
13 |
Choice.D |
This is not correct because it seems to have miscalculated the surface area of the triangular prism |
692.24 sq.cm |
14 |
Answer |
Option |
C |
15 |
SumUp |
Can you summarize what you’ve understood in the above steps? |
|
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