Lesson 5.45.4 Small Group · Group 1
Group 1 · Set BSecond form · new problems, same idea
Learning target With my small group, I can find the area of a composite figure by decomposing it into basic shapes, including a regular polygon split into triangles, and adding or subtracting the areas — one step at a time, with support.
Remember5.4 Small Group · Group 1
Split a composite figure into shapes you know, find each area, and add the pieces that are joined together. To find the area of a composite figure, split it into simple shapes. Find each area. Then add them.
Words: Composite Figure (Figura compuesta)Decompose (Descomponer)Add (Sumar)Subtract (Restar)Formula (Fórmula)
-
1Complete each step, then write the final answer.
An L-shaped garden is made of a 7 m by 3 m rectangle and a 2 m by 4 m rectangle. Find its total area.
Show your workHint Find each area: 7 × 3 and 2 × 4. The pieces are joined, so add.
Final answer: -
2Complete each step, then write the final answer.
An L-shape is made of an 8 cm by 3 cm rectangle and a 2 cm by 4 cm rectangle. Find its total area.
Show your workHint Find each rectangle. They are joined, so add.
Final answer: -
3Complete each step, then write the final answer.
A yard is a rectangle 20 m by 15 m. A square pool is in the yard. Each side of the pool is 6 m. The rest of the yard is grass. How much of the yard is grass?
Show your workHint The pool is not grass. Find the whole yard, then take the pool away.
Final answer: -
4Complete each step, then write the final answer.
A table top is a regular octagon. It splits into 8 congruent triangles. Each has a base of 2.5 ft and a height of 3 ft. Find the area of the table top.
Show your workHint Find one triangle first. It will be a decimal. Then multiply by 8.
Final answer:
Explain your thinkingHow do you decide whether to add or subtract the pieces of a shape? Use the wall and the house shape.
Sentence starter I add when the pieces are ___. · I subtract when a piece is ___.