Explanation

Explanation

Explanation

To find the perimeter of a semi-circle, we need to consider two parts:

1. The half of the circumference of the circle, which is $frac{1}{2} times 2pi r = pi r$.
2. The diameter of the circle, which is $2r$.

• The radius $r = 700$ meters.

1. Calculate the curved part (half of the circumference):

   $$text{Curved part} = pi times r = pi times 700 approx 3.1416 times 700 approx 2199.12 , text{m}$$

2. Add the diameter:

   $$text{Diameter} = 2 times r = 2 times 700 = 1400 , text{m}$$

3. Total perimeter:

   $$text{Perimeter} = text{Curved part} + text{Diameter} = 2199.12 , text{m} + 1400 , text{m} = 3599.12 , text{m}$$

4. Convert the result to kilometers:

   $$3599.12 , text{m} = 3.6 , text{km}$$

Explanation

Explanation

Explanation

Explanation

1. 
   

2. $$a^2 + b^2 = 25 - 12 = 13.$$

Explanation

Explanation

Let's define the ages of the three people:

• Let David's age be $D$.
• John's age is 4 years more than David's, so John's age is $D+4$.
• Joe's age is 2 years less than David's, so Joe's age is$D-2$.

The sum of their ages is given as 41:

$$(D)+(D+4)+(D-2)=41$$

1. Simplify the equation:

   $$D + D + 4 + D - 2 = 41$$ $$3D + 2 = 41$$

2. Subtract 2 from both sides:

   $$3D = 39$$

3. Divide both sides by 3:

   $$D = 13$$

So, David is 13 years old.

• John's age is $D + 4 = 13 + 4 = 17$ years.
• In 8 years, John's age will be: $$17 + 8 = 25 text{ years}$$

Explanation