Calculate Side Length AC in Deltoid with Area 48 cm² and Diagonal 6 cm

Deltoid Area with Diagonal Calculations

Shown below is the deltoid ABCD.

Diagonal DB = 6

The area of the deltoid is 48 cm².

Calculate the side AC.

S=48S=48S=48666DDDAAABBBCCC

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Calculate AC
00:03 We'll use the formula for calculating the area of a kite
00:07 (diagonal times diagonal) divided by 2
00:12 We'll substitute appropriate values and solve for AC
00:22 We'll multiply by 2 to eliminate the fraction
00:35 Isolate AC
00:43 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Shown below is the deltoid ABCD.

Diagonal DB = 6

The area of the deltoid is 48 cm².

Calculate the side AC.

S=48S=48S=48666DDDAAABBBCCC

2

Step-by-step solution

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

  • Step 1: Use the formula for the area of a deltoid.

  • Step 2: Substitute the known values into the formula.

  • Step 3: Solve for the unknown diagonal AC AC .

Now, let's work through each step:

Step 1: The area of a deltoid is given by the formula:

Area=12×AC×DB \text{Area} = \frac{1}{2} \times AC \times DB

Step 2: Substitute the given values into the formula:

48=12×AC×6 48 = \frac{1}{2} \times AC \times 6

Step 3: Solve for AC AC .

First, simplify the equation:

48=3×AC 48 = 3 \times AC

Now, divide both sides by 3 to isolate AC AC :

AC=483=16 AC = \frac{48}{3} = 16

Therefore, the solution to the problem is AC=16cm AC = 16 \, \text{cm} .

3

Final Answer

16

Key Points to Remember

Essential concepts to master this topic
  • Formula: Area of deltoid equals half the product of diagonals
  • Technique: Substitute Area = 48, DB = 6 into 12×AC×6 \frac{1}{2} \times AC \times 6
  • Check: Verify 12×16×6=48 \frac{1}{2} \times 16 \times 6 = 48

Common Mistakes

Avoid these frequent errors
  • Using wrong area formula for deltoids
    Don't use triangle area formulas like base × height ÷ 2 for deltoids = completely wrong answer! Deltoids are special quadrilaterals where diagonals are perpendicular. Always use the deltoid formula: Area = ½ × diagonal₁ × diagonal₂.

Practice Quiz

Test your knowledge with interactive questions

Look at the deltoid in the figure:

555666

What is its area?

FAQ

Everything you need to know about this question

What exactly is a deltoid and how is it different from other shapes?

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A deltoid is a special quadrilateral (4-sided shape) where the diagonals are perpendicular to each other. Unlike rectangles or parallelograms, deltoids use a unique area formula based on their perpendicular diagonals.

Why do we multiply the diagonals and then divide by 2?

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When diagonals are perpendicular, they create four right triangles inside the deltoid. The formula 12×d1×d2 \frac{1}{2} \times d_1 \times d_2 calculates the total area of all four triangles combined!

How do I know which diagonal is which in the problem?

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It doesn't matter! The area formula works with either diagonal first. Whether you write 12×AC×DB \frac{1}{2} \times AC \times DB or 12×DB×AC \frac{1}{2} \times DB \times AC , you'll get the same answer.

What if I get stuck on the algebra part?

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Break it down step by step: 48 = 3 × AC means "3 times what number equals 48?" Divide both sides by 3 to find AC = 16. Practice makes perfect!

Can I use this formula for any quadrilateral?

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No! This formula only works when the diagonals are perpendicular (meet at 90°). For other quadrilaterals like rectangles or trapezoids, you need different formulas.

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