If a rectangle has the length l and the width w, the perimeter P, will be: Could you have found the perimeter of this rectangle if you only knew its width? For kids who write the 4 as the minuend ask "What is 4 less than 10? Have the student explain which expression is preferred for this purpose and why.
Include an explanation of the rationale for writing expressions in equivalent form. Finally, we will use the solution to find the lengths of the missing sides. These result in one-step equations.
Guide the student to give a justification for equivalence by referencing properties of operations e. The student cannot relate the expressions to specific aspects of the context of the problem.
If needed, review how the perimeter of a rectangle is calculated. Moving Forward The student cannot identify equivalent expressions. What is this expression telling you to do to the width of the rectangle? Rectangle Formula The lesson on the perimeter of a rectangle will cover the basics needed to use this formula.
I will walk around to help as needed. What do the variables represent in each expression? Example Given a rectangle with the length of 5ft and the width of 3ft. Does not give a specific explanation. Verify that the student understands the difference between mathematically equivalent and looks the same.
All the sides edges of a square have the same length. Explains how to find the perimeter of a rectangle. Problem 8 is perhaps the hardest problem because the length is described as 4 units less than twice the width.
Explain the relationship between the two expressions using appropriate mathematical vocabulary. Example Given a parallelogram with the side lengths of 8 inches and 6 inches. Questions Eliciting Thinking What does x represent in this problem? The first four all involve regular polygons. Got It The student provides complete and correct responses to all components of the task.
Square Formula The lesson on the perimeter of a square will provide the explanation and examples needed to understand this formula.
If students do not know what the term "regular" means they should carefully read problem 1. Modeling The Perimeter For the guided practice problems, I will have students go step by step through the problems.
What are the coefficients and why are the coefficients added and not multiplied? Questions Eliciting Thinking What do the numbers and variables represent in the second expression?
This should help to have a width of w and a length of 2w - 4.Question Find an algebraic expression. The perimeter of a rectangle, given that the length is x yards and the width is 10 yards shorter. The perimeter of a rectangle, given that the length is x yards and the width is 10 yards shorter.
After thinking about and using one specific expression for the perimeter of a rectangle, they now extend their thinking to equivalent expressions for the same quantity. The open-ended last question is intended to generate a classroom discussion led by the teacher.
A Rectangle's Perimeter. The perimeter of a rectangle is equal to the sum of all the sides. However, since a rectangle's opposite sides are congruent, we only need to know the length and width. We can write this in an equation this way: P = l + w + l + w.
where P is the perimeter, l is the length of the rectangle and w is its width. SOLUTION: Write the expression for the perimeter of a rectangle with a length that is 4 centimeters longer than three times its width Algebra -> Rectangles -> SOLUTION: Write the expression for the perimeter of a rectangle with a length that is 4 centimeters longer than three times its width Log On.
The perimeter of any rectangle is the sum of the lengths of its sides.
A rectangle has two pairs of equal length sides, so its perimeter is width + width + length + length, or in other words twice the sum of the width and the length. As students share I will write an expression on the board to represent the perimeter of each shape. Students will help provide the expression or expressions.
For the triangle I will have: 3 + 4 + 5 = 12 units. For the rectangle I will have: 7 + 7 + 12 + 12 = 38 units or 2(7+12) = 38 or some other variation.Download