Examples with solutions for Parts of a Triangle: Using the theorem: The median of a triangle divides it into two triangles of the same area

Exercise #1

In front of you the next triangle:

Since AD is the median

Since the area of the triangle ADB is equal to 15.

Find the area of the triangle ABC.

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Video Solution

Step-by-Step Solution

To solve this problem, we'll employ the theorem which states that the median of a triangle divides it into two triangles of equal area. Given that AD AD is a median of ABC \triangle ABC , it divides ABC \triangle ABC into ADB \triangle ADB and ADC \triangle ADC .

Step 1: Recognize the properties of a median. The median AD AD implies:
- Area of ADB= \triangle ADB = Area of ADC \triangle ADC .
- Given Area of ADB=15 \triangle ADB = 15 , hence Area of ADC=15 \triangle ADC = 15 .

Step 2: Compute the total area of ABC \triangle ABC :
- Total Area of ABC= \triangle ABC = Area of ADB+ \triangle ADB + Area of ADC=15+15=30. \triangle ADC = 15 + 15 = 30.

Thus, the area of triangle ABC \triangle ABC is 30 \boxed{30} .

Answer

30

Exercise #2

In front of you the next triangle:

Since AD is the median

Since the area of the triangle ABC is equal to 32.

Find the area of the triangle ADC.

AAABBBCCCDDD

Video Solution

Step-by-Step Solution

To solve this problem, we'll use the property that a median of a triangle divides it into two triangles of equal area. Given the area of ABC \triangle ABC is 32:

  • Since AD AD is the median, it divides ABC \triangle ABC into two triangles ABD \triangle ABD and ADC \triangle ADC of equal area.
  • Thus, the area of ADC=12×Area of ABC=12×32=16. \triangle ADC = \frac{1}{2} \times \text{Area of } \triangle ABC = \frac{1}{2} \times 32 = 16.

Therefore, the area of triangle ADC \triangle ADC is 16 16 .

Answer

16

Exercise #3

Look at the triangle below.

AD is the median and height.

Calculate the area of triangle ABC.

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Video Solution

Answer

60