The question I received from the students today is a medium problem.
I'll tell you the answer firstIt is 404,850 yuan。Did you see if you got your calculations right?
Let's analyze how to calculate this problem.
The total cost of laying plastic on the runway is known as the unit price per square meter, so the area of the runway needs to be calculated again. RunwayTotal cost = unit price Total runway area
The area of the runway consists of two rectangular (red) and two semi-circular runways (green).
It was observed that 2 small rectangles can be combined into one large rectangle, the length is ab, and the width = bc-de.
The 2 semi-circular runways can be combined into two circles. Large circle - small circle = area of 2 semi-circular runways.
So, let's calculate the area of the rectangle, and then calculate the area difference between the two circlesThe difference between the area of the rectangle + the area of the circle = the total area of the runway.
Rectangular area
ab×（bc-de）
2400 (sq.m.).
How do you calculate the difference between the areas of two circles?This is the hard part. The area formula for a circle is s= r.
The radius of the great circle is set to r, r=bc 2=50 2=25 (m).
The radius of the small circle is set to r, r=de 2=20 2=10 (meters).
These two conditions are more difficult to find, and this question is also difficult here.
So, the area difference of the circle = the area of the arc runway = r - r
s=π×25²-π10²
3.14, so,Arc runway area = 314×525=1648.5 (sqm).
The entire runway area = rectangular runway area + arc runway area.
4048.5 (sqm).
Total**=Total area Unit price=40485 100 = 404850 (yuan).
The above is this math problem for the 4th grade of elementary school, I don't know if everyone thinks I understand it?If you think it's clear, please give it a thumbs up. Thank you, little masters.