Examples with solutions for Area of a Trapezoid: How many times does the shape fit inside of another shape?

Exercise #1

Rectangle ABCD is separated into a trapezoid (AKCD) and a right triangle (KBC).

DC = 14 cm

AD = 5 cm

KB = 4 cm

How many triangles identical to triangle KBC are needed to create the trapezoid AKCD?

141414555444AAABBBCCCDDDKKK

Video Solution

Step-by-Step Solution

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

  • Step 1: Calculate the area of triangle KBC.
  • Step 2: Determine the relevant dimensions for trapezoid AKCD and calculate its area.
  • Step 3: Divide the area of the trapezoid by the area of the triangle to determine how many triangles fit into the trapezoid.

Now, let's work through each step:

Step 1: Calculate the area of triangle KBC.
KBC is a right triangle where KB=4cmKB = 4 \, \text{cm} and BC=5cmBC = 5 \, \text{cm} (since AD=5cmAD = 5 \, \text{cm} is a vertical line segment in the rectangle, BCBC must be equal to ADAD).
The area of triangle KBC is given by:

AreaKBC=12×base×height=12×4×5=10cm2 \text{Area}_{KBC} = \frac{1}{2} \times \text{base} \times \text{height} = \frac{1}{2} \times 4 \times 5 = 10 \, \text{cm}^2

Step 2: Calculate the area of trapezoid AKCD.
For trapezoid AKCD, AKAK is the shorter parallel side, and DC=14cmDC = 14 \, \text{cm} is the longer parallel side. The height is the same as the height of rectangle AD or BC, h=5cmh = 5 \, \text{cm}.
To find AKAK, since KB=4cmKB = 4 \, \text{cm} and total AB=14cmAB = 14\, \text{cm}, thus AK=ABKB=144=10cmAK = AB - KB = 14 - 4 = 10\, \text{cm}.
The area of trapezoid AKCD is given by:

AreaAKCD=12×(AK+DC)×h=12×(10+14)×5=12×24×5=60cm2 \text{Area}_{AKCD} = \frac{1}{2} \times (AK + DC) \times h = \frac{1}{2} \times (10 + 14) \times 5 = \frac{1}{2} \times 24 \times 5 = 60 \, \text{cm}^2

Step 3: Calculate how many triangles KBC fit into trapezoid AKCD.
To find how many triangles fit into the trapezoid, divide the area of trapezoid by the area of the triangle:

AreaAKCDAreaKBC=6010=6 \frac{\text{Area}_{AKCD}}{\text{Area}_{KBC}} = \frac{60}{10} = 6

Therefore, the solution to the problem is that 6 triangles identical to triangle KBC are needed to create the trapezoid AKCD.

Answer

6

Exercise #2

Given the rectangle ABCD which was separated into a trapezoid and a right triangle

AB=16 KC=14 BC=6

How many triangles identical to the yellow triangle are needed to complete the given trapezoid?

141414161616666CCCKKKAAABBBDDD

Video Solution

Answer

15

Exercise #3

Given a rectangle ABCD which separated into a trapezoid and a right triangle

AB=12 KC=8 BC=4

How many triangles identical to the yellow triangle are needed to complete the given trapezoid?

121212444888AAAKKKBBBCCCDDD

Answer

5

Exercise #4

Given a rectangle ABCD that was separated into a trapezoid and a right triangle.

DC=14 AD=5 KB=4

How many triangles identical to the yellow triangle are needed to complete the given trapezoid?

141414555444AAAKKKCCCDDDBBB

Video Solution

Answer

6

Exercise #5

How many times does the triangle fit in the trapezoid?

333333333333333666333

Video Solution

Answer

3