Calculate Trapezoid Area: Finding Area with Sides 2X and 3Y

Area Formula with Algebraic Variables

Calculate the area of the trapezoid in the diagram.

2X2X2X3Y3Y3YXXX

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Find the area of the trapezoid
00:03 We'll use the formula for calculating the area of a trapezoid
00:07 (Sum of bases(AB+DC) multiplied by height(H))/2
00:15 Let's substitute appropriate values according to the given data and solve for the area
00:31 Open parentheses properly - multiply each factor by X
00:45 Separate each factor and divide by 2
00:50 Simplify what's possible
00:58 And that's the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Calculate the area of the trapezoid in the diagram.

2X2X2X3Y3Y3YXXX

2

Step-by-step solution

To determine the area of the trapezoid, we will use the formula for the area of a trapezoid:

A=12×(Base1+Base2)×Height A = \frac{1}{2} \times (\text{Base}_1 + \text{Base}_2) \times \text{Height}

From the problem, the two bases are 2X2X and 3Y3Y. The height is XX.

Substituting into the formula, we have:

A=12×(2X+3Y)×X A = \frac{1}{2} \times (2X + 3Y) \times X

Simplifying the expression inside the parenthesis gives:

A=12×(2X+3Y)×X=12×(2X×X+3Y×X) A = \frac{1}{2} \times (2X + 3Y) \times X = \frac{1}{2} \times (2X \times X + 3Y \times X)

Distributing XX through the terms inside the parenthesis gives:

A=12×(2X2+3XY) A = \frac{1}{2} \times (2X^2 + 3XY)

Continuing the simplification:

A=12×2X2+12×3XY A = \frac{1}{2} \times 2X^2 + \frac{1}{2} \times 3XY

Which simplifies to:

A=X2+1.5XY A = X^2 + 1.5XY

Therefore, the area of the trapezoid is X2+1.5XY X^2 + 1.5XY cm².

Through comparison, this expression matches the given choice: x2+1.5xy x^2+1.5xy cm², which corresponds to choice 33.

Thus, the correct area of the trapezoid is x2+1.5xy x^2 + 1.5xy cm².

3

Final Answer

x2+1.5xy x^2+1.5xy cm².

Key Points to Remember

Essential concepts to master this topic
  • Formula: Trapezoid area = ½ × (base₁ + base₂) × height
  • Technique: Distribute: ½ × (2X + 3Y) × X = X² + 1.5XY
  • Check: Verify dimensions match: bases 2X, 3Y and height X ✓

Common Mistakes

Avoid these frequent errors
  • Confusing which measurements are bases versus height
    Don't assume the longest side is always the height = wrong area calculation! In this trapezoid, the parallel sides (2X and 3Y) are the bases, not the slanted sides. Always identify parallel sides as bases and perpendicular distance as height.

Practice Quiz

Test your knowledge with interactive questions

Calculate the area of the trapezoid.

555141414666

FAQ

Everything you need to know about this question

How do I know which sides are the bases in a trapezoid?

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The bases are the parallel sides. In this diagram, 2X and 3Y are labeled on the top and bottom horizontal lines, making them parallel. The height X is the perpendicular distance between them.

Why is the answer x² + 1.5xy and not 2.5xy?

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You must distribute correctly! When you multiply (2X + 3Y) × X, you get 2X² + 3XY. Then multiply by ½ to get X² + 1.5XY, not just 1.5XY.

What does the 1.5 coefficient mean in the final answer?

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The 1.5 comes from ½ × 3 = 1.5. When distributing ½(3XY), you get 1.5XY. This shows how the trapezoid formula affects each term differently.

Can I use decimal 1.5 or should I write it as a fraction?

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Both 1.5XY and ³⁄₂XY are correct! In this context, 1.5 is clearer and matches the multiple choice format, but fractions work too.

What if I mixed up which variable was which?

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Check the diagram carefully! The height is always perpendicular to the bases. Here, X is clearly marked as the vertical height, while 2X and 3Y are the horizontal parallel bases.

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