Find the area of a rectangular trapezoid with two smaller sides equal to 6 cm and a large angle equal to 135 °.

Let us draw the height from the top of the trapezoid ABCD to the base of AD.

Then in the formed right-angled triangle СНD the angle НСD = BCD – BCН = 135 – 90 = 45.

Then the angle НDС = НСD = 45, and the triangle СНD is isosceles, СН = DH.

Since the trapezoid is rectangular, ВA is parallel to CH, and therefore ABCH is a rectangle, then AB = CH = 6 cm, BC = AH = 6 cm.

CH = DH = 6 cm.

Then AD = AH + DH = 6 + 6 = 12 cm.

Then the area of the trapezoid is:

Savsd = (ВС + АD) * СН / 2 = (6 + 12) * 6/2 = 54 cm2.

Answer: Savsd = 54 cm2.