Fractional Lengths in Triangles and Prisms

Warmup

Activity #1

Find Area of a Triangle with Fractional Lengths & Missing Side Lengths.

  • Study the diagrams below and answer the questions that follow.

Find the area of Triangle A in square centimeters. Show your reasoning.

The area of Triangle B is 8 square units. Find the length of b. Show your reasoning.

The area of Triangle C is 54/5 square units. What is the length of h? Show your reasoning.

Activity #2

Finding Missing Sides Lengths of Similar Triangles with Decimal Lengths.

  • Use cubes or the applet below to help you answer the following questions.​

(1.) How many cubes with edge lengths of  inch are needed to fill the cube below?

(2.) What is the volume in cubic inches, of a cube with edge lengths of   inch? Explain or show your reasoning.

Activity #3

Find Volume of a Prism by Counting Cubes.

  • Use cubes or the applet to help you answer the following questions.​

(1.) Four cubes are piled in a single stack to make a prism. Each cube has an edge length of ½ inch. Sketch the prism, and find its volume in cubic inches.

(2.) For each prism, record in the table how many -inch cubes can be packed into the prism.

Challenge #1

The area of Triangle B is 8 square units. Find the length of b. Show your reasoning.

Challenge #2

Challenge #3

Which expression can be used to find how many cubes with edge length of 13 unit fit in a prism that is 5 units by 5 units by 8 units?

Quiz Time

https://www.ixl.com/math/grade-5/perimeter-with-fractional-side-lengths