In a rectangular trapezoid ABCD, the lateral side AB = 10 cm, the larger base AD

In a rectangular trapezoid ABCD, the lateral side AB = 10 cm, the larger base AD = 18 cm, the angle D is 45 degrees. Find the area of this trapezoid.

From the top of the obtuse angle C we draw the height CH. Quadrangle ABCН is a rectangle since CH is height, and the trapezoid is rectangular. Then AB = CH = 10 cm, and BC = AН.

In a right-angled triangle СDН, one of its acute angles is 45, then this triangle is isosceles and right-angled, and DН = СН = 10 cm.

Then the length of the segment AH = AD – DH = 18 – 10 = 8 cm, then BC = AH = 8 cm.

Determine the area of the trapezoid.

Savsd = (ВС + АD) * СН / 2 = (8 + 18) * 10/2 = 130 cm2.

Answer: The area of the trapezoid is 130 cm2.



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