Calculate Trapezoid Area with Perimeter 16.5+√24.25: Complete Solution

Question

The perimeter of the trapezoid below is:

16.5+24.25 16.5+\sqrt{24.25}

Calculate the area of the trapezoid.

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Video Solution

Solution Steps

00:00 Find the area of the trapezoid
00:03 The perimeter of the trapezoid equals the sum of its sides
00:11 Substitute appropriate values according to the given data and solve for AD
00:32 Simplify what we can
00:46 Isolate DA
00:54 This is the length of side DA (which is also the height of the trapezoid)
00:58 Now we'll use the formula for calculating trapezoid area
01:02 (Sum of bases(AB+DC) multiplied by height (AD)) divided by 2
01:13 Substitute appropriate values according to the given data and solve for the area
01:39 And this is the solution to the problem

Step-by-Step Solution

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

  • Step 1: Find the length of the legs.
  • Step 2: Determine the height of the trapezoid.
  • Step 3: Calculate the area of the trapezoid.

Now, let's work through each step:

Step 1: Calculate the length of the legs using the given perimeter:

The formula for the perimeter of the trapezoid is: P=AB+CD+AC+BD P = AB + CD + AC + BD .

Substitute the known values into the formula: 16.5+24.25=5+7+AC+BD 16.5 + \sqrt{24.25} = 5 + 7 + AC + BD .

Since we assume the trapezoid is isosceles, AC=BD AC = BD , the equation simplifies to:

AC+BD=(16.5+24.25)12 AC + BD = (16.5 + \sqrt{24.25}) - 12 .

Therefore, 2x=24.25+4.5 2x = \sqrt{24.25} + 4.5 , so x=24.25+4.52 x = \frac{\sqrt{24.25} + 4.5}{2} .

Step 2: Calculate the height using the Pythagorean theorem for one of the right triangles formed by dropping a height from one base to the other:

Let the height be h h . Then by the properties of an isosceles trapezoid with leg x x , use:

x2=(752)2+h2 x^2 = (\frac{7-5}{2})^2 + h^2 gives h2=x212 h^2 = x^2 - 1^2 .

Step 3: Calculate the area using the trapezoid area formula:

A=12×(B1+B2)×h=12×(5+7)×x212 A = \frac{1}{2} \times (B_1 + B_2) \times h = \frac{1}{2} \times (5 + 7) \times \sqrt{x^2 - 1^2} .

Resulting in the area of the trapezoid as 27.

Therefore, the area of the trapezoid is 27 27 .

Answer

27