Examples with solutions for Area of a Deltoid: Applying the formula

Exercise #1

Look at the deltoid in the figure:

777444

What is its area?

Video Solution

Step-by-Step Solution

Let's begin by reminding ourselves of the formula for the area of a kite

Diagonal1×Diagonal22 \frac{Diagonal1\times Diagonal2}{2}

Both these values are given to us in the figure thus we can insert them directly into the formula:

(4*7)/2

28/2

14

Answer

14

Exercise #2

Look at the deltoid in the figure:

555666

What is its area?

Video Solution

Step-by-Step Solution

To solve the exercise, we first need to know the formula for calculating the area of a kite:

It's also important to know that a concave kite, like the one in the question, has one of its diagonals outside the shape, but it's still its diagonal.

Let's now substitute the data from the question into the formula:

(6*5)/2=
30/2=
15

Answer

15

Exercise #3

ACBD is a deltoid.

AD = AB

CA = CB

Given in cm:

AB = 6

CD = 10

Calculate the area of the deltoid.

666101010AAACCCBBBDDD

Video Solution

Step-by-Step Solution

To solve the exercise, we first need to remember how to calculate the area of a rhombus:

(diagonal * diagonal) divided by 2

Let's plug in the data we have from the question

10*6=60

60/2=30

And that's the solution!

Answer

30

Exercise #4

ABDC is a deltoid.

AB = BD

DC = CA

AD = 12 cm

CB = 16 cm

Calculate the area of the deltoid.

161616121212CCCAAABBBDDD

Video Solution

Step-by-Step Solution

First, let's recall the formula for the area of a rhombus:

(Diagonal 1 * Diagonal 2) divided by 2

Now we will substitute the known data into the formula, giving us the answer:

(12*16)/2
192/2=
96

Answer

96 cm²

Exercise #5

Shown below is the deltoid ABCD.

The diagonal AC is 8 cm long.

The area of the deltoid is 32 cm².

Calculate the diagonal DB.

S=32S=32S=32888AAABBBCCCDDD

Video Solution

Step-by-Step Solution

First, we recall the formula for the area of a kite: multiply the lengths of the diagonals by each other and divide the product by 2.

We substitute the known data into the formula:

 8DB2=32 \frac{8\cdot DB}{2}=32

We reduce the 8 and the 2:

4DB=32 4DB=32

Divide by 4

DB=8 DB=8

Answer

8 cm

Exercise #6

Given the deltoid ABCD

Find the area

666444AAABBBCCCDDD

Video Solution

Step-by-Step Solution

To find the area of deltoid ABCDABCD, we will use the known formula for the area of a deltoid based on its diagonals. Let's perform the calculation step-by-step:

  • Step 1: Identify the diagonals
    From the problem, the diagonals are given as 4 cm and 6 cm.
  • Step 2: Apply the area formula
    The area of a deltoid is calculated using the formula: A=12×d1×d2 A = \frac{1}{2} \times d_1 \times d_2
  • Step 3: Calculate the area
    Substitute the diagonal lengths into the formula: A=12×4×6 A = \frac{1}{2} \times 4 \times 6
  • A=12×24=12A = \frac{1}{2} \times 24 = 12 cm²

Thus, the area of deltoid ABCDABCD is 12\mathbf{12} cm².

Answer

12 12 cm².

Exercise #7

Given the deltoid ABCD

Find the area

777555AAABBBCCCDDD

Video Solution

Step-by-Step Solution

To solve this problem, we need to calculate the area of the deltoid ABCDABCD using the given lengths of its diagonals. The formula for the area of a deltoid (kite) is:

A=12×d1×d2 A = \frac{1}{2} \times d_1 \times d_2

Where d1d_1 and d2d_2 are the lengths of the diagonals. From the diagram, we know:

  • Diagonal AC=7AC = 7 cm
  • Diagonal BD=5BD = 5 cm

Substituting these values into the formula, we have:

A=12×7×5 A = \frac{1}{2} \times 7 \times 5

Calculating this gives:

A=12×35=17.5 A = \frac{1}{2} \times 35 = 17.5

Therefore, the area of the deltoid ABCDABCD is 17.517.5 cm².

The correct answer from the given choices is:

17.5 17.5 cm².

Answer

17.5 17.5 cm².

Exercise #8

Given the deltoid ABCD

Find the area

999666AAADDDCCCBBB

Video Solution

Step-by-Step Solution

To solve the problem of finding the area of the deltoid (kite) ABCD, we will apply the formula for the area of a kite involving its diagonals:

The formula is:
Area=12×d1×d2\text{Area} = \frac{1}{2} \times d_1 \times d_2

Where d1d_1 and d2d_2 are the lengths of the diagonals. From the problem’s illustration:

  • Diagonal d1d_1 (AC): Not visible in numbers, assumed to be covered internally or derived from setup, but logically follows as one given median-symmetry related.
  • Diagonal d2d_2 (BD): The vertical line gives a length of 6 cm6\text{ cm} from point B to D on the vertical axis.

The image references imply through markings that their impact in shape is demonstrated via convergence of matching altitudes and isos of plot. The diagonal proportion can be referred via an intercept mark mutual to setup if not altered by mistake redundantly.

Thus: Calculated area <=>12×6×9=27 cm2<=> \frac{1}{2} \times 6 \times 9 = 27\text{ cm}^2

The calculated area matches with the choice option:

  • The correct choice is 27 cm227 \text{ cm}^2, corresponding to provided option 4.

Therefore, the area of the deltoid is 27 cm2\boxed{27 \text{ cm}^2}.

Answer

27 27 cm².

Exercise #9

Given the deltoid ABCD

Find the area

101010777CCCBBBAAADDD

Video Solution

Step-by-Step Solution

To solve this problem, we need to calculate the area of the deltoid using the formula for the area in terms of diagonals:

  • Identify the two diagonals: AC=10AC = 10 cm and BD=7BD = 7 cm.
  • Use the formula for the area of a deltoid: A=12×d1×d2 A = \frac{1}{2} \times d_1 \times d_2 .
  • Substitute the values of the diagonals into the formula: A=12×10×7=702=35 A = \frac{1}{2} \times 10 \times 7 = \frac{70}{2} = 35 .

Thus, the area of the deltoid is 35 cm2\textbf{35 cm}^2.

Therefore, the solution to the problem is 35 cm2\textbf{35 cm}^2, which corresponds to choice 3.

Answer

35 35 cm².

Exercise #10

Given the deltoid ABCD

Find the area

999888AAADDDCCCBBB

Video Solution

Step-by-Step Solution

To solve this problem, we'll calculate the area of the deltoid ABCDABCD using the formula for the area of a kite or deltoid, which depends on its diagonals.

  • Step 1: Identify the given information
    The given diagonals are AC=9AC = 9 cm and BD=8BD = 8 cm.

  • Step 2: Apply the area formula for a deltoid
    The area AA of a deltoid with perpendicular diagonals is given by:

  • A=12×d1×d2 A = \frac{1}{2} \times d_1 \times d_2

  • Step 3: Perform the calculation
    Substitute the given diagonal lengths into the formula:
    A=12×9×8 A = \frac{1}{2} \times 9 \times 8
    A=12×72 A = \frac{1}{2} \times 72
    A=36 A = 36

Thus, the area of the deltoid ABCDABCD is 36 36 cm².

Answer

36 36 cm².

Exercise #11

Look at the deltoid ABCD below.

Given in cm:

AC = 7

DB = 5

Calculate the area of the deltoid.

777555AAABBBCCCDDD

Video Solution

Step-by-Step Solution

To find the area of the deltoid ABCDABCD, we will use the area formula for a deltoid:

A=12×d1×d2 A = \frac{1}{2} \times d_1 \times d_2

where d1d_1 and d2d_2 are the lengths of the diagonals.

Given:

  • d1=AC=7cmd_1 = AC = 7 \, \text{cm}
  • d2=DB=5cmd_2 = DB = 5 \, \text{cm}

Substitute the given lengths into the formula:

A=12×7×5 A = \frac{1}{2} \times 7 \times 5

A=12×35 A = \frac{1}{2} \times 35

A=17.5cm2 A = 17.5 \, \text{cm}^2

Therefore, the area of the deltoid is 17.5cm2 17.5 \, \text{cm}^2 .

Answer

17.5 cm².

Exercise #12

Look at the deltoid ABCD below.

Diagonal DB = 4

The area of the deltoid is 24 cm².

Calculate the diagonal AC.

S=24S=24S=24444AAABBBCCCDDD

Video Solution

Step-by-Step Solution

To find the length of diagonal AC of the deltoid, follow these steps:

  • We know the formula for the area of a deltoid (kite) given by S=12×d1×d2 S = \frac{1}{2} \times d_1 \times d_2 . Here, S=24cm2 S = 24 \, \text{cm}^2 , d1=AC d_1 = AC , and d2=BD=4cm d_2 = BD = 4 \, \text{cm} .
  • Substitute the known values into the formula: 24=12×AC×4 24 = \frac{1}{2} \times AC \times 4 .
  • Simplify the equation: 24=2×AC 24 = 2 \times AC because 12×4=2 \frac{1}{2} \times 4 = 2 .
  • Solve for AC AC by dividing both sides by 2: AC=242 AC = \frac{24}{2} .
  • This simplifies to AC=12 AC = 12

Therefore, the length of diagonal AC is 12cm 12 \, \text{cm} .

Answer

12 cm

Exercise #13

Shown below is the deltoid ABCD.

The diagonal AC is 3 cm long.

The area of the deltoid is 18 cm².

Calculate the diagonal DB.

S=18S=18S=18333AAABBBCCCDDD

Video Solution

Step-by-Step Solution

The goal here is to find the diagonal DB DB of the deltoid. Given:

  • Diagonal AC=3 AC = 3 cm
  • Area of the deltoid =18 = 18 cm2^2

We utilize the formula relating the diagonals and area of a deltoid:

Area=12×d1×d2 \text{Area} = \frac{1}{2} \times d_1 \times d_2

Here, d1=3 d_1 = 3 cm (given as diagonal AC AC ) and the area is given as 18 cm2^2. We are solving for d2=DB d_2 = DB .

Substituting the known values into the formula:

18=12×3×DB 18 = \frac{1}{2} \times 3 \times DB

First, multiply both sides by 2 to clear the fraction:

36=3×DB 36 = 3 \times DB

Now, solve for DB DB by dividing both sides by 3:

DB=363=12cm DB = \frac{36}{3} = 12 \, \text{cm}

Therefore, the diagonal DB DB of the deltoid is 12cm 12 \, \text{cm} .

Answer

12 cm

Exercise #14

Given the deltoid ABCD

Find the area

888111111AAADDDCCCBBB

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Identify the given information.
  • Step 2: Use the appropriate formula for area calculation.
  • Step 3: Perform the calculation using the formula.

Now, let's work through each step:
Step 1: We recognize that the vertical diagonal AC=8AC = 8 cm and the horizontal diagonal BD=11BD = 11 cm.
Step 2: We'll use the formula for the area of a deltoid (kite), given by
A=12×d1×d2A = \frac{1}{2} \times d_1 \times d_2, where d1d_1 and d2d_2 are the lengths of the diagonals.
Step 3: Plugging in our values, we get:
A=12×8×11A = \frac{1}{2} \times 8 \times 11
A=12×88A = \frac{1}{2} \times 88
A=44A = 44 cm².

Thus, the area of the deltoid is 44 44 cm².

Answer

44 44 cm².

Exercise #15

Given the deltoid ABCD

Find the area

555999AAADDDCCCBBB

Video Solution

Step-by-Step Solution

To solve the problem of finding the area of the deltoid ABCD, we can apply the following method:

  • Step 1: Identify the diagonals:
    From the problem, AC=5 AC = 5 cm and BD=9 BD = 9 cm are the lengths of the diagonals.
  • Step 2: Apply the area of deltoid formula:
    When diagonals intersect perpendicularly in a kite or deltoid shape, the area A A is given by:
    A=12×d1×d2 A = \frac{1}{2} \times d_1 \times d_2
    where d1=5 d_1 = 5 cm and d2=9 d_2 = 9 cm are the diagonals.
  • Step 3: Substitute and calculate:
    A=12×5×9 A = \frac{1}{2} \times 5 \times 9
    A=12×45 A = \frac{1}{2} \times 45
    A=22.5 A = 22.5 cm²

Therefore, the area of the deltoid ABCD is 22.5 22.5 cm².

Answer

22.5 22.5 cm².

Exercise #16

Given the deltoid ABCD

Find the area

555888AAADDDCCCBBB

Video Solution

Step-by-Step Solution

To solve for the area of deltoid ABCDABCD, we employ the formula for the area of a deltoid given its diagonals:

  • The formula is Area=12×d1×d2\text{Area} = \frac{1}{2} \times d_1 \times d_2, where d1d_1 and d2d_2 are the diagonals.
  • From the problem, the length of the first diagonal (d1d_1) is 5 units and the second diagonal (d2d_2) is 8 units.

Now, substituting these values into the formula:

Area=12×5×8=12×40=20\text{Area} = \frac{1}{2} \times 5 \times 8 = \frac{1}{2} \times 40 = 20

Thus, the area of the deltoid is 20cm2\mathbf{20 \, \text{cm}^2}.

The correct choice from the given options is choice 2.

Answer

20 20 cm².

Exercise #17

Given the deltoid ABCD

Find the area

999151515AAADDDCCCBBB

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Identify the given information: The lengths of diagonals are 9 cm and 15 cm.
  • Apply the appropriate formula for the area of a deltoid.
  • Perform the necessary calculations.

Now, let's work through each step:
Step 1: We are given that diagonal d1=9 d_1 = 9 cm and diagonal d2=15 d_2 = 15 cm.
Step 2: We'll use the formula for the area of a deltoid: Area=12×d1×d2 \text{Area} = \frac{1}{2} \times d_1 \times d_2 .
Step 3: Plugging in our values, we get: Area=12×9×15=12×135=67.5 cm2 \text{Area} = \frac{1}{2} \times 9 \times 15 = \frac{1}{2} \times 135 = 67.5 \text{ cm}^2

Therefore, the solution to the problem is 67.5 67.5 cm².

Answer

67.5 67.5 cm².

Exercise #18

Given the deltoid ABCD

Find the area

13131317.517.517.5AAADDDCCCBBB

Video Solution

Step-by-Step Solution

To find the area of the deltoid, we will use the formula for the area of a kite which is based on the lengths of its diagonals:

Area=d1×d22\text{Area} = \frac{d_1 \times d_2}{2}

Given:

  • d1=AC=13d_1 = AC = 13 cm, and
  • d2=BD=17.5d_2 = BD = 17.5 cm.

Now, substitute these values into the formula:

Area=13×17.52\text{Area} = \frac{13 \times 17.5}{2}

Calculating inside the parentheses:

13×17.5=227.513 \times 17.5 = 227.5

Therefore, the area is:

Area=227.52=113.75\text{Area} = \frac{227.5}{2} = 113.75 cm²

The area of the deltoid ABCD is 113.75113.75 cm².

The correct answer choice is: 113.75113.75 cm².

Answer

113.75 113.75 cm².