Lesson 5.95.9 Small Group · Group 2
Group 2 · Set BSecond challenge form · new problems, same idea
Learning target I can find the area of a regular polygon by decomposing it into triangles, explain why the method works, and use it on a problem I have not seen before.
Remember5.9 Small Group · Group 2
A regular polygon is a set of equal triangles from the center, so you can multiply to find the area or divide to find a missing length. Area = number of sides × area of one triangle. You can work backward to find a missing height or side.
Words: Regular Polygon (Polígono regular)Decompose (Descomponer)Triangle (Triángulo)Composite (Compuesto)Formula (Fórmula)
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1Complete each step, then write the final answer.
A regular octagon is made of 8 equal triangles. Its area is 120 square inches. Each triangle has a height of 6 inches. How long is each side?
Show your workFinal answer: -
2Complete each step, then write the final answer.
A regular octagon has sides of 8 in. Its area is about 310.4 square inches. Find the height of each center triangle.
Show your workFinal answer: -
3Complete each step, then write the final answer.
A pool cover is a regular pentagon with sides of 6 ft. Each center triangle has a height of 4.1 ft. The cover costs $2 for each square foot. About how much does it cost?
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4Complete each step, then write the final answer.
A regular hexagon and a regular pentagon each have a perimeter of 120 cm. The hexagon's center triangles have a height of 17.3 cm. The pentagon's have a height of 16.5 cm. Which has more area? How much more?
Show your workFinal answer: