Step-by-step explanation:
Before we answer, the area of a Circle given it radius is

The area of a circle given it diameter is

So let answers question 1-4.
1. The area is 

2. The area is

3.

4.

For the 5th problem, circumference is 

where d is the diameter and

where r is the radius.
A circumference of 100 m means the radius is 50 because 


So this means the area is

 
        
             
        
        
        
Answer:
Obtuse Triangle
Step-by-step explanation:
When there is an angle with a measurement greater than 90 degrees, the triangle is an obtuse triangle. 
 
        
             
        
        
        
Answer:
6.5%
Step-by-step explanation:
Percentage error formula = 
|Estimated value - Real value|/Real value × 100
From the above question,
Estimated value = 17,466
Real value = 16,400
Percentage error = |17,466 - 16,400|/16,400 × 100
= 1066/16,400 × 100
= 0.065 × 100
= 6.5%
Therefore, the percent error = 6.5%
 
        
                    
             
        
        
        
I don't understand the question