Math Problem Statement

Perhatikan gambar berikut. Hitunglah: a. Luas segitiga ABD, b. Luas segitiga BCD, c. Luas bangun ABCD

Solution

Let's break down the problem from the image you've uploaded. The question asks to calculate the following:

Given Information:

  • A trapezoid ABCDABCD with:
    • AD=9cmAD = 9 \, \text{cm}
    • AB=14cmAB = 14 \, \text{cm}
    • DE=24cmDE = 24 \, \text{cm}
    • BD=12cmBD = 12 \, \text{cm}

To Calculate:

a. The area of triangle ABDABD.
b. The area of triangle BCDBCD.
c. The area of trapezoid ABCDABCD.

I will start by calculating the areas step by step.

a. Area of Triangle ABD:

To find the area of triangle ABDABD, we can use the formula for the area of a triangle: Area of triangle=12×base×height\text{Area of triangle} = \frac{1}{2} \times \text{base} \times \text{height} Here, the base is AB=14cmAB = 14 \, \text{cm} and the height is AD=9cmAD = 9 \, \text{cm}. Area of ABD=12×14×9=63cm2\text{Area of } ABD = \frac{1}{2} \times 14 \times 9 = 63 \, \text{cm}^2

b. Area of Triangle BCD:

For triangle BCDBCD, we use the same formula. The base is BD=12cmBD = 12 \, \text{cm} and the height is the perpendicular distance between lines DEDE and BDBD, which is given as AD=9cmAD = 9 \, \text{cm} because it's a trapezoid and the heights are the same. Area of BCD=12×12×9=54cm2\text{Area of } BCD = \frac{1}{2} \times 12 \times 9 = 54 \, \text{cm}^2

c. Area of Trapezoid ABCD:

The area of the trapezoid can be found using the formula for the area of a trapezoid: Area of trapezoid=12×(Base1+Base2)×height\text{Area of trapezoid} = \frac{1}{2} \times (\text{Base}_1 + \text{Base}_2) \times \text{height} Here, the two bases are AB=14cmAB = 14 \, \text{cm} and DE=24cmDE = 24 \, \text{cm}, and the height is AD=9cmAD = 9 \, \text{cm}. Area of trapezoid ABCD=12×(14+24)×9=12×38×9=171cm2\text{Area of trapezoid ABCD} = \frac{1}{2} \times (14 + 24) \times 9 = \frac{1}{2} \times 38 \times 9 = 171 \, \text{cm}^2

Summary:

  • a. Area of triangle ABD = 63cm263 \, \text{cm}^2
  • b. Area of triangle BCD = 54cm254 \, \text{cm}^2
  • c. Area of trapezoid ABCD = 171cm2171 \, \text{cm}^2

Would you like further clarifications or details?

Related Questions:

  1. How do we calculate the area of a triangle using Heron's formula?
  2. What is the significance of height in calculating the area of trapezoids?
  3. How can you calculate the area of an irregular shape using decomposition?
  4. Can we calculate the perimeter of the trapezoid ABCD?
  5. How do you apply Pythagoras' theorem to find the height of a triangle in certain cases?

Tip:

Always identify and label known dimensions clearly when solving for areas, especially in complex shapes like trapezoids and triangles.

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Math Problem Analysis

Mathematical Concepts

Geometry
Trapezoid
Triangles

Formulas

Area of triangle: 0.5 × base × height
Area of trapezoid: 0.5 × (Base1 + Base2) × height

Theorems

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Suitable Grade Level

Grades 6-8