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Lesson Example Discussion Quiz: Class Homework

Lesson

Title: Surface area of 3D shapes(sphere, prism, cylinder)

Grade: 4-a Lesson: S3-L2

Explanation: Hello students, let us learn a new topic in geometry today with definitions, concepts, examples, and worksheets included.

Lesson:

Definition: Sphere

A sphere is a three-dimensional geometric shape, perfectly round like a ball, defined as the set of all points equidistant from a fixed center. The distance from the center to any point on its surface remains constant.

The formula gives the surface area (A) of a sphere: \$"A" = 4πr^2\$

$1$

Explanation: The image displays a sphere with a surface area of 100π square centimeters, computed using the formula \$"A" = 4πr^2\$, where the radius is 5 units.

Definition: Cylinder

A cylinder is a 3D shape with two parallel circular bases connected by a curved surface. Its defining dimensions are the radius and height.

The formula for the surface area of a cylinder is given by:

A = \$2πr^2 + 2πrh\$

The first term \$2πr^2\$ represents the combined area of the two circular bases, and the second term 2πrh represents the lateral surface area.

$2$

Explanation: The cylinder has a base area of 18π square units with a radius of 3 units, calculated using the

formula \$2πr^2\$.

Definition: Prism

A prism is a three-dimensional geometric shape with two parallel and congruent polygonal bases connected by rectangular faces.

The formula gives the surface area (A) of a prism: A = 2B + PH

$3$

Explanation: A rectangular prism, with a base area of 24 square units, a perimeter of 16 units, and a height of 5 units, has a surface area of \$2 times 24 + 16 times 5 = 128\$.