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Understanding the dimensions of shapes plotted on a coordinate plane is essential. This lesson delves into the methods of determining the area and perimeter of various figures using their coordinates. For instance, the length and width of a rectangle can be identified using the coordinates of its vertices. Similarly, the area of a triangle can be calculated using its vertices' coordinates. Concepts like the Distance Formula are employed to determine the lengths of sides, and subsequently, the perimeter of figures. This knowledge is not just theoretical; it has practical applications in real-world scenarios where spatial measurements are required.
Show less Show more expand_more| Student Learning Objectives: |
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| | 7 Theory slides |
| | 11 Exercises - Grade E - A |
| | Each lesson is meant to take 1-2 classroom sessions |
Try your knowledge on these topics.
State the coordinates of the points plotted on the plane.
Determine whether a triangle with side lengths 4, 5, and 6 is a right triangle.
Use the Pythagorean Theorem to find the missing side length. Round the answer to one decimal place.
Calculate MN by using the Distance Formula.
Find the perimeter of the given polygon.
Calculate the area of the rectangle.
The coordinates of the vertices of a polygon can be used to identify the type of the polygon.
Emily's sister completed her first 1-mile run. Emily wants to make a congratulatory card in the shape of a triangle for her. She wants the card to have the form of an equilateral triangle. However, she lost her ruler and made all the measurements by eyeballing it.
Izabella wants to buy a plot of land for her garden. This rectangular plot of land should have a minimum area of 30 square meters and a perimeter no less than 20 meters to have enough space. She knows the coordinates of the vertices of the plot of land.
Next, by substituting the endpoints of the chosen segments into the Distance Formula, their lengths can be calculated.
| Length | Width | |
|---|---|---|
| Endpoints | ( - 5, 2) and ( 3, 5) | ( 3, 5) and ( 5, 0) |
| Substitute | l=sqrt(( 3-( - 5))^2+( 5- 2)^2) | w=sqrt(( 5- 3)^2+( 0- 5)^2) |
| Evaluate | l≈ 8.5 | w≈ 5.4 |
Now that the length and the width are known, the area and the perimeter of the rectangle can be determined.
| Area | Perimeter | |
|---|---|---|
| Formula | A=wl | P=2(w+l ) |
| Substitute | A= 5.4( 8.5) | P=2( 5.4+ 8.5) |
| Evaluate | A=45.9 | P=27.8 |
Since these values are greater than the area and the perimeter of the plot of land that Izabella wanted to buy, they satisfy the given requirements. Therefore, Izabella should buy this plot of land.
On a test, Kriz is asked to find the area and perimeter of a triangle illustrated on a coordinate plane.
Kriz wrote that the area of △ MNK is 15 square units and its perimeter is 24 units. Is Kriz correct?
Next, the side lengths of △ MNK need to be calculated by using the Distance Formula. The calculations for MN are shown below.
Substitute values
By following the same procedure, NK and MK can be calculated.
| d = sqrt((x_2-x_1)^2 + (y_2-y_1)^2) | |||
|---|---|---|---|
| Side | Endpoints | Substitute | Evaluate |
| MN | M( - 2, - 2) and N( 3, 4) | MN=sqrt(( 3-( - 2))^2+( 4-( - 2))^2) | MN≈ 7.8 |
| NK | N( 3, 4) and K( 4, - 2) | NK=sqrt(( 4- 3)^2+( - 2- 4)^2) | NK≈ 6.1 |
| MK | M( - 2, - 2) and K( 4, - 2) | MK=sqrt(( 4-( - 2))^2+( - 2-( - 2))^2) | MK=6 |
Now, the perimeter of △ MNK can be calculated by adding the three side lengths of the triangle. P=7.8+6.1+6 ⇕ P=19.9 The perimeter of △ MNK is 19.9 units. Next, its area will be found. Recall that the area of a triangle is half the product of the base and its corresponding height. A=bh/2 In this formula, b is the base of the triangle and h its corresponding height. In a triangle, the base and its corresponding height are perpendicular. If MK is the base, then the height is the perpendicular segment to MK through N. In the diagram, it can be seen that the length of this segment is 6 units.
Finally, by substituting b= 6 and h= 6, the area of △ MNK can be calculated.
Therefore, the area of the triangle is 18 square units and its perimeter 19.9 units. This means that Kriz was not correct.
The plan of a flat is represented on a coordinate plane. The plan has the shape of a compound geometric figure.
Calculate the area and the perimeter of the plan. Round each value to one decimal place.
The value of m can be calculated by substituting (- 5,1) and (0,4) into the Distance Formula.
Substitute values
By adding the lengths of the exterior sides, the perimeter of the plan can be calculated. P=3+5.8+6+6+6+5 ⇕ P=31.8 The perimeter of the figure is 31.8 units. The area of a compound figure is equal to the sum of the geometric figures' areas that make the compound figure. From the diagram, it can be seen that the flat has a square, a rectangular, and a triangular room.
The area of a square is equal to the square of a side length. It has been previously found that, in the plan, each side of the square room is 6 units long.
By raising 6 to the power of two, the area of the square can be determined. \begin{gathered} A_\text{square}=6^2\\ \Updownarrow \\ A_\text{square}=36\text{ units}^2 \end{gathered}
The area of a rectangle is equal to the product of its length and width. From the diagram, it can be seen that the length of the rectangle is 5 units and the width is 3 units.
By multiplying 3 by 5, the area of the rectangle can be found. \begin{gathered} A_\text{rectangle}=3(5)\\ \Updownarrow \\ A_\text{rectangle}=15\text{ units}^2 \end{gathered}
The area of a triangle is half the product of its base and its height. Analyzing the diagram, it can be seen that the base and height of the triangle are b=5 units and h=3 units, respectively.
By substituting these values into the formula for the area of a triangle, its area can be calculated.
Gather all the areas that have been found. A_(square)&=36units^2 A_(rectangle)&=15units^2 A_(triangle)&=7.5units^2 By adding these values, the area of the compound figure can be calculated. \begin{gathered} A_\text{total}=36+15+7.5\\ \Updownarrow\\ A_\text{total}=58.5\text{ units}^2 \end{gathered}
The diagram illustrates a triangle on a coordinate plane, and gives the coordinates of the vertices.
Calculate the area of the triangle. If needed, round the answer to one decimal place.
By substituting the coordinates of the vertices into the Distance Formula, the side lengths can be calculated.
| d = sqrt((x_2-x_1)^2 + (y_2-y_1)^2) | |||
|---|---|---|---|
| Side | Endpoints | Substitute | Evaluate |
| a | ( 2, 3) and ( 3, 7.5) | a=sqrt(( 3- 2)^2+( 7.5- 3)^2) | a≈ 4.6 |
| b | ( 3, 7.5) and ( 7, 1) | b=sqrt(( 7- 3)^2+( 1- 7.5)^2) | b≈ 7.6 |
| c | ( 2, 3) and ( 7, 1) | c=sqrt(( 7- 2)^2+( 1- 3)^2) | c≈ 5.4 |
Next, the side lengths will be substituted into the formula for the semi-perimeter to find the value of s.
Now that the semi-perimeter of the triangle is known, its area can be found using Heron's Formula.
Substitute values
The area of the triangle is approximately 12.3 square units.
With the topics seen in this lesson, the challenge presented at the beginning can be solved. It consisted in determining whether the card made by Emily has the shape of an equilateral, an isosceles, or a scalene triangle.
Note that the bottom side is a horizontal segment. Therefore, its length is equal to the difference of the x-coordinates of the endpoints. A( 0,0) and C( 8,0) ⇓ AC= 8- 0 AC=8 The lengths of the other two sides can be calculated using the Distance Formula.
| d = sqrt((x_2-x_1)^2 + (y_2-y_1)^2) | |||
|---|---|---|---|
| Side | Endpoints | Substitute | Evaluate |
| AB | A( 0, 0) and B( 4, 7) | AB=sqrt(( 4-( 0))^2+( 7- 0)^2) | AB≈ 8.1 |
| BC | B( 4, 7) and C( 8, 0) | BC=sqrt(( 8- 4)^2+( 0- 7)^2) | BC≈ 8.1 |
As it can be seen, AB and BC have the same length. However, they are a little longer than AC. Therefore, Emily's card has a shape of an isosceles triangle.
Use Heron's Formula to find the area of the triangle.
We are going to determine area of a triangle using Heron's Formula. A=sqrt(s(s-a)(s-b)(s-c)) In this formula a, b, and c are the side lengths and s is half the perimeter. First we need to find these. Then we will calculate the triangle's area with the formula.
We will use the Distance Formula to calculate a, which is the length of AB.
Let's repeat this procedure for the other two sides to find b and c.
| Side | Points | sqrt((x_2-x_1)^2+(y_2-y_1)^2) | Length |
|---|---|---|---|
| b | ( 1, 2) ( 1, - 6) |
sqrt(( 1- 1)^2+( - 6- 2)^2) | 8 |
| c | ( - 2, - 2) ( 1, - 6) |
sqrt(( 1-( - 2))^2+( - 6-( - 2))^2) | 5 |
Next, we are going to determine s, which is half the perimeter. Recall that the perimeter is the sum of the side lengths.
Therefore, s equals 9 units.
Let's substitute the values we have found into Heron's Formula.
The triangle's area is 12 units^2.
For the function f(x), find the distance between the points (4,f(4)) and (7,f(7)). f(x) = 2x + 3 Round your answer to one decimal place.
We have been asked to find the distance between two points. (4,f(4)) (7,f(7)) The x-coordinates are given. To find the corresponding y-coordinates, f(4) and f(7), we will substitute the x-values into the function.
| x | f(x)=2x+3 | Evaluate | (x,y) |
|---|---|---|---|
| 4 | f( 4)=2( 4)+3 | f(4)=11 | ( 4, 11) |
| 7 | f( 7)=2( 7)+3 | f(7)=17 | ( 7, 17) |
To determine the distance between the two points, we use the Distance Formula.
The distance between the two points is approximately 6.7 units.