Examples with solutions for Diagonals: Calculation of the diagonal using properties

Exercise #1

Look at the following rectangle:

AAABBBCCCDDD1312

AB = 12

AC = 13

Calculate the area of the triangle BCD.

Video Solution

Step-by-Step Solution

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

  • Step 1: Use the Pythagorean Theorem to calculate the length of AD AD .
  • Step 2: Calculate the area of triangle BCD \triangle BCD .

Step 1: Given AB=12 AB = 12 and AC=13 AC = 13 , we use the Pythagorean Theorem to find AD AD .

AC2=AB2+AD2    132=122+AD2 AC^2 = AB^2 + AD^2 \implies 13^2 = 12^2 + AD^2 169=144+AD2    AD2=25    AD=5 169 = 144 + AD^2 \implies AD^2 = 25 \implies AD = 5

Step 2: Knowing the sides AD=5 AD = 5 (height of the rectangle) and AB=12 AB = 12 (base of the rectangle), triangle BCD \triangle BCD will have the base BC=12 BC = 12 and the height BD=5 BD = 5 .

The area of triangle BCD \triangle BCD is:

AreaBCD=12×base×height=12×12×5=30 \text{Area}_{\triangle BCD} = \frac{1}{2} \times \text{base} \times \text{height} = \frac{1}{2} \times 12 \times 5 = 30

Therefore, the area of triangle BCD \triangle BCD is 30.

Answer

30

Exercise #2

Look at the following rectangle:

AAABBBCCCDDD17

BD = 17

Calculate the length of the diagonal AC.

Video Solution

Answer

17

Exercise #3

Given the following rectangle:

AAABBBCCCDDDOOO5

O is the intersection point of the diagonals.

Given: BO=5

Calculate the length of the diagonal BD.

Video Solution

Answer

10

Exercise #4

Look at the following rectangle:

AAABBBCCCDDDOOO5

O is the intersection point of the diagonals.

BO = 5

Calculate the length of the diagonal AC.

Video Solution

Answer

10

Exercise #5

Look at the following rectangle:

AAABBBCCCDDDOOO6.56.5

O is the intersection point of the diagonals of the rectangle.

AO = O

D = 6.5

Calculate the length of the diagonal AC.

Video Solution

Answer

13

Exercise #6

Look at the following rectangle:

AAABBBCCCDDD34

AD = 3

AB = 4

Calculate the length of the diagonal AC.

Video Solution

Answer

5