IXL | Surface area of pyramids

A rectangular pyramid is shown below.

Which diagram is a net for this pyramid?

What is the surface area of the rectangular pyramid?

square millimeters

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Learn with an example

question

A triangular pyramid is shown below.

Which diagram is a net for this pyramid?

What is the surface area of the triangular pyramid?

square millimeters

key idea

A net shows all the faces of a three-dimensional figure.

A triangular pyramid has four triangular faces. Its surface area is the sum of the areas of all four faces.

solution

Four faces make up the triangular pyramid:

one triangular face with a base of 13 millimeters and a height of 11.3 millimeters
three triangular faces with a base of 13 millimeters and a height of 12 millimeters

This is a net for the pyramid. It shows all of the faces and, when folded up, will form the pyramid.

To find the surface area, add up the areas of all four faces.

There is one triangular face with a base of 13 millimeters and a height of 11.3 millimeters. Find its area.

(

)

(

11.3

)

(

146.9

)

73.45

square millimeters

There are three triangular faces with a base of 13 millimeters and a height of 12 millimeters. Find the area of one of them.

(

)

(

)

(

156

)

square millimeters

Finally, find the sum of the areas of all four triangular faces.

(

)

73.45

234

73.45

307.45

The surface area of the triangular pyramid is 307.45 square

millimeters.

Looking for more? Try these:

Lesson: What is surface area?

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Not feeling ready yet? These can help:

CC.1Surface area of cubes and prisms

GG.6Area of triangles

Lesson: What is surface area?

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