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Zorluk: ZorPerimeter and Area of 2D Figures

A cross-section of an irrigation canal has the shape of an isosceles trapezoid. The flat bottom of the canal is 1010 meters wide, the open water surface at the top is 2020 meters wide, and the vertical depth of the canal is 1212 meters. To prevent seepage, a waterproof lining is applied only to the flat bottom and the two slanted sides of the canal. What is the total length, in meters, of the canal's cross-section that receives this lining?

Cevap: 36 meters

Cevap

36
The lined portion consists of the flat bottom and the two slanted sides. By dropping perpendicular altitude lines from the top corners to the bottom plane, two identical right triangles are formed on the left and right edges. The horizontal base of each right triangle is half of the difference between the top and bottom widths: (20−10)/2=5(20 - 10) / 2 = 5 meters. The vertical height of the canal is given as 1212 meters. Using the Pythagorean theorem (a2+b2=c2a^2 + b^2 = c^2), the length of each slanted side is 52+122=169=13\sqrt{5^2 + 12^2} = \sqrt{169} = 13 meters. The total length of the waterproof lining is the sum of the bottom width and the two slanted sides: 10+13+13=3610 + 13 + 13 = 36 meters.

Adım Adım Çözüm

1
Calculate the horizontal difference on each side of the trapezoid.
5 meters
To form a right triangle to calculate the slanted side, we must distribute the difference between the top and bottom widths equally to both sides.
2
Apply the Pythagorean theorem to find the length of the slanted sides.
13 meters
Each slanted side acts as the hypotenuse of a right triangle with legs of 5 meters (horizontal) and 12 meters (vertical height).
3
Sum the lengths of the sections that receive the lining.
36 meters
The lining is only applied to the bottom (10 meters) and the two slanted sides (13 meters each). The top is open and excluded.

Anahtar Kavram

Calculating the partial perimeter of a composite/trapezoidal figure using the Pythagorean theorem.
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